At some point in 1999, Barack Obama, then a young and virtually unknown Illinois state senator, was considering running for a seat in the House of Representatives representing Illinois’ First Congressional District—which includes parts of the South Side of Chicago and some southern suburbs—against longtime incumbent Bobby Rush.

So on a visit to Washington, D.C., he stopped in at the office of Lynn Sweet, the Washington bureau chief for the Chicago Sun-Times.

It’s what everyone does when they’re in a tough race: introduce themselves to Ms. Sweet, who since 1993 has been the voice of Washington politics for the Chicago tabloid.

“When he walked in, the first thing he did was hand me this book,” said Ms. Sweet, as she settled down into a seat at Morty’s, a Washington delicatessen, for a toasted onion bagel and a Dr. Brown’s diet black cherry soda. “He walked into my office in the Press Club with his aide Dan Shomon and he hands me his book and says, ‘This is my story.’ And I said, ‘Oooh. Okay?’”

Mr. Obama gave her a copy of Dreams from My Father, his 1995 memoir, which Ms. Sweet had no idea he had written. Ms. Sweet, who turned 57 years last week, made a crooked face.

“Probably if you saw me, you would have seen me raise—it was a silent huh? It was a silent huh. If you could hear me say, silently, huh, it raised a huh for me.” She looked like she had swallowed a few lemon slices.

“The huh is, he’s 40-something and he’s written his memoir already? I wasn’t aware of the whole story line, though; I just thought he had a memoir. I did not know that much about his life. We just met a few hours ago. If the first thing you did was say, ‘Lynn, here’s my memoir,’ I would say ‘Ooookay?’”

He was unlikely to unseat Mr. Rush (he didn’t, in fact), so she shelved the book and forgot about it. “In hindsight, I wish I had gotten the book a week beforehand. But who knew? Who knew at the time?”

She didn’t start leafing through it until June 2004, the same summer Mr. Obama was well on his way to his Senate seat and delivered his famous speech at the Democratic National Convention.

The book was an instant hit when it was re-released that year, when Ms. Sweet finally got around to reading it.

“Composite characters. Changed names. And reams of dialogue between Obama and other people that moves the narrative along but is an ‘approximation’ of the actual conversation,” she wrote in the Sun-Times. “Except for public figures and his family, it is impossible to know who is real and who is not.”

HILDY JOHNSON MEETS BEN SMITH

Ms. Sweet is not the person to think of if you think of the reporters that people like to say have given in to Barack Obama’s charms. Nor does she have an axe to grind. She is not a pledged foe of Mr. Obama the way some reporters for hometown papers become when the people they have covered emerge from their backyard to become national figures.

But even other reporters who follow her around say she’s the first to call “bullshit.”

“I don’t write a story saying how Obama came out of the rough-and-tumble of Chicago politics,” she said, quietly and forcefully in her Chicago accent—she’s lived there nearly 40 years. “Because in my experience, he was able to avoid the rough-and-tumble of Chicago politics. Au contraire! He didn’t come up through the system.”

She was now speaking from the same office where Mr. Obama had met her nine or so years before, and I suspect it hasn’t much changed since then. It’s full of memorabilia from her days from Chicago: Sun-Times baseball caps; a framed gag license plate that reads ‘SCOOP,’ accompanied by a laudatory note from then Illinois Secretary of State George Ryan, who later became governor and after a recent conviction for corruption is serving a six-year prison sentence. On the wall is a road sign indicating the Lincoln Park West neighborhood where she used to live. A broken computer sat in front of her with a sheet of paper taped to its side reading, “Shut the fuck up and type.”

“Obama came in and had a very lucky break to come in in 90-something, make some of the right connections, and have an opening,” she said. “He returned to Chicago and worked with a law firm that gave him a lot of political network advantages, and started looking around for some office to run for, found this opening in the State Senate where he put himself in it. Now that’s not coming through the rough-and-tough of Chicago politics. And then once he knocked his opponent off the ballot, he represented a safe Democratic district, and that if he chose to, he could have represented until he stopped working. O.K.?”

Prior to this year’s political season, Ms. Sweet was a largely unknown tabloid reporter from a regional newspaper who had never seriously covered a presidential campaign. The Sun-Times, a tabloid that not even Rupert Murdoch could glam up, wasn’t exactly known for its national reach. But with Mr. Obama’s ascent, Ms. Sweet has suddenly emerged as one of the most important voices in the campaign.

“When you’re watching a press conference with Obama and he’s trying to weasel out of something, you’ll hear him getting interrupted three or four times and he’s usually saying ‘Lynn! Wait, Lynn,’” said Glenn Thrush, the Newsday reporter covering the Democratic primary. “Of all the people who cover Obama, she’s the one who holds him most accountable.”

“She is an in-the-moment specialist,” said Jeff Zeleny, the New York Times Obama reporter, who covered him with the Chicago Tribune as well. “Her role, and I think it is carved out intentionally, is in-the-moment blow-by-blow and a chronicler of what he’s doing.”

“She’s followed Obama’s career for years and is well sourced among other Illinois elected officials, political operatives and within the donor community,” said Ben LaBolt, Mr. Obama’s spokesman. “She got her reporting roots in Chicago and knows the town and the people here as well as anyone else.”

“I’m one of the people who have been paying close attention in a very close way on a day-to-day level for a long, long time and I come from the same area,” said Ms. Sweet. “I know his neighborhood, I know his neighbors, I know the political context that he came from, and that’s useful to covering him at this stage. That’s part of understanding the whole picture.”

May 16 was a busy Friday for Ms. Sweet. She had a morning interview on a Washington-based NPR show with local legend Diane Rehm. She spoke about Mr. Obama and the election—and Congress—for the better part of an hour. After the show, she took this reporter out for that bagel at Morty’s, before she had to make her way to NBC’s Washington bureau for a TV interview.

Between these, there was a radio interview to be done with a local Chicago radio station, and she was running late.

“Taxi! Taxi!” she shouted from the curb, spinning in a pirouette along it. If a cab were to come down the street, it could not miss her, but there weren’t any. It was time to walk.

“Okay, hustle! Hustle!” she said to me. She was wearing a heavy red rain jacket and put up her hood. “As a reporter, shouldn’t you come prepared for the weather?” she asked, quite seriously. But it wasn’t raining.

“I have an inexhaustible energy,” she said. Ms. Sweet hadn’t slept much the night before because the roof at her house was leaking, and she was anxious because she still hadn’t heard back from the roofer.

About 15 minutes later, in the television station’s lobby, there was a live Obama speech being carried with no sound on one of the three flat-screens; the crawler indicated he was talking about Iran.

“Oh, no, this is bad, this is bad,” she muttered repeatedly to herself. “Can you please pick up the volume? Helloooo, excuse me, can you pick up the volume?”
She was speaking to a security guard, who was helpless.

“This is bad, this is frustrating,” she said.

She wanted to blog this, and it was clear she was already behind on the day’s biggest story: Mr. Obama was attacking George W. Bush for his comments in Israel the day before. Ms. Sweet is an active blogger: She posts several times a day with a lot of videos and a lot of raw text—statements and responses by campaigns. She likes to be first, and she often is. Her blog is a go-to Obama stop.

“On her blog, she posts a record of all the news and all the reporting that is out there on Obama,” said Mr. LaBolt, the spokesman.

“She’s Hildy Johnson meets Ben Smith,” said Mr. Thrush, the Newsday reporter. “She’s taken to this blog like an 18-year old. She uses the new medium in an old-fashioned way.”

“I’m no suburban bridge-player!” you can almost hear her saying, like Hildy in His Gal Friday. “I’m a newspaperman!”

She’s the steampunk of the Beltway blogosphere. She has one of those old-time name-and-number AOL e-mail addresses (lsweet3022@aol.com), and when you get an e-mail from her, the subject line reads, in case you’re not sure, “from lynn sweet.” Even though she blogs a ton, she describes it inexactly. (“I need to do a blog on that,” she said at one point about an idea for a post.) On the campaign trail, she wears what other campaign reporters have described as a miner’s hat with a little light at the top, but really it’s just an elastic band with a light attached to it, like one you’d have in front of your bicycle. On a trip during an ice storm in Iowa with journalist Alicia Sams, she was in the front seat taking notes, light propped up top, and every time she looked up, she promptly blinded Ms. Sams.

REMEMBER WAUKEGAN!

But her prominence in pixels has also given her some television airtime, usually when an anchor wants to talk to someone about Barack Obama’s story.

“Obama has taken on issues that I tend to know a lot about in some areas with ethics, transparency and campaign finance,” she said. “If he said that his campaign is going to be on South American foreign policy, the farm bill and whether or not the U.S. should sell broadband at auction, I would say I have a lot more to do. But O.K., here it is, the guy says he’s going to be the most open, transparent president, so let’s go to the, let’s go to the—what do they do in sports? Let’s go to the replay?”

During briefings, Ms. Sweet has never been shy about acting like a pain-the-ass tabloid reporter. Back in March, Mr. Obama gave a press conference about his former donor Tony Rezko. At one point, Mr. Obama said he already answered questions about his relationship with Mr. Rezko in previous press conferences. “No, you haven’t! Are you taking about the press conference in Waukegan?” She had attended that November 2006 press conference, and there really wasn’t much discussion of him back then.

“I don’t think it is fair to suggest somehow that we have been trying to hide the bone on this,” Mr. Obama told her, according to an account in Politico.

Then, as he tried to cut the availability short, reporters waved their notebooks and tape recorders, shouting his name, and the press-sensitive Mr. Obama tried to laugh it off, saying, “Oh, wait, wait, guys, come on! I just answered like eight questions.”

“Answer a few more questions, come on!” barked out Ms. Sweet in that familiar accent, staring at him from a few feet away. He dashed off.

She was one of the few reporters who held Mr. Obama’s feet to the fire on Mr. Rezko even when most of the rest of the press decided—probably correctly—that it wasn’t going hurt him and therefore, debatably, it wasn’t worth obsessing over.

“Even though I have been away from Chicago since the end of 1993, I do come from a place where people are not shy about mixing it up a little bit if that’s what it takes to get clarity on a situation,” she said later. “I find that not to be often in Washington.”

When Andrea Mitchell introduced Lynn Sweet for her midafternoon show on MSNBC on May 16, she said, “Lynn Sweet is with the Chicago Sun-Times and has been covering him for years.”

That’s partially true. She has covered him for less than two years. She has spent the majority of her other three decades covering any other number of political stories in Chicago. Since the campaign started, she has only occasionally been on the campaign plane, and the campaign bus. Most of that is due to the problems with the Chicago Sun-Times; its parent company, Sun-Times Media, was recently delisted from the New York Stock Exchange, and it cut the paper’s staff by 20 percent. The paper is now up for sale.

As Washington chief for the paper, she represents the entire bureau. She said that with her blog, she has no editor, and the most she’ll get in the way of suggestions from another human being at the paper is an occasional suggestion on how to treat a parenthetical in a column.

In fact, it was an incredibly self-conscious decision to decide to cover Mr. Obama.

“I started looking at a lot of blogs and I realized you need a sensibility!” she said. “Why am I here? What can I give you? I suppose I could make a blog on ‘Lynn Sweet’s thoughts about … whatever!’”

That would be something of a bomb. But!

“If I had choice between writing about something Bush did, or a congressman did, or Obama, why wouldn’t I go to something I saw people were backing? I just knew from the enormous amount of coverage Obama was getting that oooh, I knew I should be all things Obama. I never had a meeting; no one ever told me to do it. It was just like, I, I just smelled the coffee. I just understood that’s what I could be about.”

But when she started the blog, she also sacrificed a lot of her reporting chops.

In the mid-1990s, she broke a story on donors in the Clinton White House in the lead-up to the Lincoln Bedroom stories.

She admits that that kind of reporting is not for her right now.

“Maybe there should be more analysis on his State Senate record, but I can’t go take the time to go back and do that unless it’s something real specific,” she said. “That’s for other people to do. Even today, I don’t have the Michelle commercial, I don’t have the Obama speech. Look at how behind I am! Obama is probably going to declare victory on Tuesday, and I was going to write a big piece about it today. Instead, I’m up here, so where do you want me to go back and look—without a tip—to go? I can’t do that.”

“I know I’m recognized as the Obama specialist because I am an Obama specialist,” she said. “I mean, just to make sure, when I was in Chicago, I made sure I drove past his house. I was in Chicago last week just to see what there is to see. I didn’t have to go, I just wanted to go. I just wanted to have more facts at my disposal. I realized I hadn’t seen the house he used to live in, so I went by and drove by there. You never know when you need stuff. I have product in the pipeline. You don’t know when you need it. I just like stuff.”

And as her news hole increasingly decreases in the Sun-Times, her blog has just opened more space for that stuff. “No one will work harder than I am. I will never not worker harder than someone. I will never stop reporting.”