SPRINGFIELD, Ill. (AP) -- The Illinois race for an open Senate seat may be the biggest political battle of 2010, at least when it comes to bragging rights.
This is the seat held by Barack Obama before he moved to the White House. It would be a major victory for Republicans to take the president's former seat out of the Democratic column in a state that, on paper, is strongly Democratic.
To pull off that coup, Republican leaders are backing Mark Kirk, a commander in the Naval Reserve and five-term congressman with moderate views on issues like gun control and abortion.
Kirk outrages some conservative activists, who consider him a traitor to fundamental Republican principles, but that hasn't translated into significant support for any of his rivals in the primary. One group recently canceled a debate because it couldn't find evidence that any of Kirk's opponents reached even 5 percent in opinion polls.
There's more competition in the Democratic primary race, and more vulnerabilities.
State Treasurer Alexi Giannoulias is the apparent front-runner based on name recognition and fundraising. He also oversaw an investment program that lost $150 million that Illinois families had set aside to pay for college. It doesn't help that his only other job was with his family's troubled bank.
David Hoffman, former prosecutor and inspector general for the city of Chicago, may be Giannoulias' most aggressive challenger, but he hasn't had the money to reach most voters.
Cheryle Jackson, head of the Chicago Urban League, has a natural political base as the only Black candidate in the field. She also was a high-ranking aide to disgraced former Gov. Rod Blagojevich, something that opens her to questions about ethics and judgment.
Attorney Jacob Meister has presented himself as an outsider, someone who is more in touch with business owners than with politicians. He, too, lacks the money for a major campaign.
The Democratic nominee, whoever that is, will face significant political hurdles.
The president's party traditionally struggles in midterm elections. That struggle is likely to be even more severe than usual unless the economy picks up or Democrats manage to pass a popular version of health care reform.
"This is going to be a very difficult year for Democrats," Hoffman admitted during a recent debate.
Complicating things even further, this particular Senate seat is entangled in the Blagojevich scandal.
The former governor is accused of, essentially, trying to sell the seat and name the buyer as Obama's replacement. Even after his arrest, Blagojevich went ahead and appointed Roland Burris to the seat. Burris gave conflicting, incomplete answers about how he came to get that appointment, which triggered an ethics investigation and made Burris so unpopular that he decided not to run for a full term.
Republicans argue that Illinois voters should make a clean break from the past and send Democrats a message on ethics by backing the GOP candidate.
"We have to have leaders who do not become criminals," Kirk said when he launched his campaign. "We are currently ruled by a corrupt one-party state that is growing in arrogance and greed."
Kirk's critics, both Republicans and Democrats, portray him as a flip-flopper who takes whatever position is most politically expedient.
Exhibit A is his vote on "cap and trade" legislation meant to limit pollution that contributes to climate change.
Kirk voted for the bill in the House, outraging conservatives who consider the measure a massive tax meant to address a nonexistent problem. After beginning his Senate run, Kirk said he had voted for cap and trade because it would have been good for his congressional district but that he now felt it would be bad for the state as a whole. If he faced the bill as a senator, Kirk said, he would vote against it.
Kirk also was mocked when it came to light that he suggested Sarah Palin might want to endorse him while she was in Chicago to talk with Oprah Winfrey. Kirk and Palin have some fundamental differences on the issues, and he questioned her credentials to serve when she was a candidate for vice president.
Republican Senate candidate Patrick Hughes argues that electing Kirk wouldn't be significantly different from electing a Democrat.
"I am running against the establishment pick, a 'Republican' who voted for bank bailouts, cap and trade, and millions in earmarks for his campaign donors," said Hughes, a Hinsdale real estate developer. "We cannot forget his votes for partial birth abortions and his 'F' rating from the (National Rifle Association)."
Kirk also faces criticism that he is too Republican.
Giannoulias, who often campaigns as if it's clear he and Kirk will be the nominees, argues that Kirk was an enthusiastic supporter of President George W. Bush and policies that left the United States with a staggering deficit and shaky economy.
Giannoulias uses a similar argument against Hoffman, alleging that Hoffman favors tax breaks for the rich and free trade policies that would send American jobs overseas.
Hoffman denies the charges and responds that voters should worry about whether Giannoulias, at just 33, has the experience and judgment to serve them well in the Senate.
Meanwhile, Jackson argues both men are launching attacks instead of solving voters' problems.
"Who's going to help them get jobs?" Jackson asked in a debate. "Who's going to help them stay in their homes? Who's going to help them put food on the table?"