With all 503 precincts in the 8th Congressional District finally counted late Wednesday afternoon, Republican Joe Walsh appears to have won Democratic incumbent Melissa Bean seat by a slim 553-vote margin.
Bean, however, is not conceding the race and a spokesman said it could be days before final results are known.
According to unofficial results, Walsh had 97,403 votes, or 48.5 percent of the total, to Bean's 96,850, or 48.3 percent, with all precincts tallied.
Green Party candidate Bill Scheurer was third with 3.2 percent of the vote.
Walsh declared victory at 4 a.m. Wednesday, despite leading by less than 800 votes at the time with six Cook County precincts awaiting counting.
"This was a race won by a people's movement," Walsh said. "Melissa Bean had more money than I did. I didn't have a ton of outside party support. But the people stood up and were counted."
Bean spokesman Jonathan Lipman said the campaign is still waiting for possibly thousands of provisional and absentee ballots to be counted.
"This election is still too close to call," he said. "We will continue to work to understand the will of the voters."
Lipman the race is unlikely to be resolved Wednesday.
Should the numbers hold up, Walsh said he looks forward to being part of a Republican-controlled Congress that shares many of his goals.
"I think it's a huge responsibility," he said. "If we blow it, if the Republicans go to D.C. and don't stop the spending, then I believe we'll be in real trouble in two years."
Walsh was dismissive of the Bean camp's suggestion that absentee or provisional votes could erase his lead.
The 8th District race was seen as something of a local litmus test as to how well the tea party movement would play in suburbia.
Walsh emerged the victor from a six-candidate GOP primary field touting himself a tea party candidate first, a Republican second. He's provided as sharp a contrast as possible to Bean's positions and voting record.
From his opposition to abortion in every instance to his support of concealed carry gun laws, there were few issues on which Walsh's position agreed with that of his three-term opponent's. One of the most comprehensive areas of their disagreement was on the value of this year's health care reform bill.
Among the many aspects of the bill Bean said she was proud of was that it bars insurance companies from denying coverage for pre-existing medical conditions.
Walsh, on the other hand, sees repeal of the health care bill as a two-step process for a Republican-controlled Congress.
The Republican overcame several early challenges with his campaign, including the foreclosure of a condo, the resignation of several staff members and a lawsuit for nonpayment filed by his former campaign manager, who later claimed it was his idea for Walsh to run on a tea party platform.
Campaign tactics became as much a part of the 8th District race as the issues, with Bean agreeing to debate Walsh publicly only once despite his taunts that she was hiding from her constituents.
The 8th District includes parts of Cook, Lake and McHenry counties.