WASHINGTON - The Democrats' latest hope for defeating U.S. Rep. Michele Bachmann sat alone at a candidate forum in Ham Lake earlier this fall, appearing next to a name card and an empty chair.

A lot has changed since then. On Thursday, businessman Jim Graves and Bachmann squared off for the second of three debates in what has become a surprisingly close race that could serve as a referendum on Bachmann's star turn in national politics.

Graves sought Thursday to use Bachmann's celebrity to her disadvantage, much as former Gov. Tim Pawlenty did when he faced off against her in the GOP presidential primaries, calling her record in Congress "nonexistent."

Meanwhile, Bachmann -- one of Congress' most conservative members -- sought to cast herself as a political independent with a bipartisan track record.

"I've worked with Democrats across the aisle to get a lot of things done and it's important we do that," Bachmann said. "I'm a very independent person." She used the debate to tout the times she had bucked her own party, saying "I didn't believe George Bush ... that we were looking at financial Armageddon," and stressing her work with Democrats on the St. Croix River bridge.

Under intense questioning during the Minnesota Public Radio debate, Bachmann offered support for vice presidential nominee Paul Ryan's Medicare plan, said the only exception on abortion should be the life of the mother and restated her opposition to federal bailouts, saying they prevented the nation's largest auto manufacturers "from going through the orderly process of bankruptcy."

Graves, who has portrayed himself as a moderate, pro-business pragmatist, said that was flawed thinking. Sometimes, he said, "you hold your nose and you do what you've got to do to keep this country up and going. We did not want to lose that sector of the economy and our whole manufacturing industry."

That the race for Minnesota's Sixth Congressional District, the state's most solidly Republican district is even close has surprised some Democrats in Washington. Bachmann's decision to hold three debates in the week before Election Day -- one live, one broadcast on radio and one on television -- now are giving an elevated profile to Graves at no cost while putting a spotlight on Bachmann's three-term record just as the race enters its most intense phase.

'Not a slam dunk'

A Graves poll last month showed Bachmann with a two-point lead, 48 to 46 percent, although a more recent poll commissioned by the Star Tribune had her up by six points, 51-45. The same newspaper poll showed that 34 percent of likely voters in the district said her presidential bid made them less likely to vote for her, while 12 percent said it made them more likely.

As Tuesday draws near, Bachmann has less room for error than ever. Democrats have tried twice to block re-election of the conservative firebrand. Both times they failed, most recently by a margin of more than 12 percentage points.

This time, close Bachmann watchers aren't expecting such a margin.

"It's a fascinating race," said St. Cloud State political scientist Stephen Frank. "It's going to be competitive." One difference, Frank said, is that Graves, a well-funded hotel magnate, seems more easygoing and personable on the campaign trail than any of his DFL predecessors. "Graves is a better candidate," Frank said. "He has enough money, and he had it early."

Graves certainly could not match the staggering $4.5 million that Bachmann raised between July and September. But he's done well enough to stay on the air, even if he can't match his opponent's barrage of TV ads.

Another difference: Unlike any of Bachmann's previous House races, this is a two-way contest with no third-party candidate.

"She comes in around 50 percent most of the time," said Carleton College political scientist Steven Schier. "In a three-way race, that's enough. In a two-way -- maybe, maybe not."

Minneapolis attorney Andy Brehm, a new-generation GOP strategist, predicts a Bachmann win. But he said she's also hurt herself and the party's brand with some of her more out-of-the-mainstream utterances. One he cited was her suggestion of a link between the human papillomavirus (HPV) vaccine and mental retardation, a comment made on national TV a year ago that was followed by the rapid unraveling of her presidential campaign.

"Minnesotans are comfortable seeing their elected officials out there on the national stage," Brehm said. "But there's no question that she's had a pattern in the last year and a half of saying inflammatory things."

Both campaigns agree that where Graves remains something of an unknown quantity, opinions are rarely lacking when it comes to Bachmann.

"The people that don't like her, don't like her," said her campaign manager, Chase Kroll. "The people that like her are happy to see their hometown girl on the national stage."

Bachmann and Graves will meet one more time on KSTP-TV this Sunday.

Staff writer Jennifer Brooks contributed to this report. Kevin Diaz is a correspondent in the Star Tribune Washington Bureau.