(CNN) - The three-way race in New York's 23rd congressional district ended Tuesday night with a surprise Democratic win - the first for the party in the reliably-Republican district since the 19th century.
Democrat Bill Owens defeated Conservative Party candidate Doug Hoffman to claim victory in a race where an internal GOP fight drew national attention - and forced the party's candidate, Dede Scozzafava, out of the campaign.
National Democrats, smarting over gubernatorial losses in New Jersey and Virginia, seized on the win, with Democratic National Committee Chairman Tim Kaine dubbing it "perhaps the most consequential race of the night."
"This race turned out to be the worst of all possible worlds for Republicans as not only did the Democrat, Bill Owens, win a seat that Democrats have not held in more than 100 years, but what occurred in New York has exposed a war within the Republican Party that will not soon end," said Kaine.
"It played itself out in Pennsylvania earlier this year when longtime Republican Senator Arlen Specter became a Democrat and is playing itself out in House, Senate and Gubernatorial races nationwide. The all out war between Republicans and the far right wing is a disaster for the Republican Party and will dog it well after today," Kaine added.
Earlier this fall, Hoffman was a clear underdog, but as the campaign to replace Rep. John McHugh drew to a close he was considered a solid favorite. He benefitted from decisions made by national Republicans after Scozzafava left the race and also was able to take advantage of decisions made by the national GOP long before it backed his candidacy.
Weeks before endorsing Hoffman's bid, the party ended its attacks on Hoffman and focused its fire solely on Bill Owens - an unusual move when the biggest threat to the Republican candidate, then holding a narrow advantage, was coming from the right.
In the race's final days, Hoffman had the momentum. A Siena survey conducted Sunday and released Monday suggested he'd gained 6 points since Scozzafava's withdrawal, and held a 5-point edge over Owens heading into Election Day.
But there were underlying signs that Hoffman couldn't count on a win, even in the heavily Republican district.
President Obama remained popular there. Hoffman increased his advantage among Republicans in the homestretch, but Owens picked up more support from independents. And the largest bloc of Scozzafava voters, Siena found Monday, hadn't gone for either of the remaining candidates, but landed in the undecided column.
Pre-withdrawal surveys also found Scozzafava's voters had higher unfavorable views of Hoffman than they did of Owens in days before she and the Watertown Times both endorsed the Democrat.
And despite the unprecedented groundswell that made him the new de facto Republican candidate, Hoffman's own campaign hadn't been without recent stumbles.
He drew headlines upstate when he was unable to answer some editorial board questions from the Watertown Times about local issues - a performance that prompted one of his high-profile backers, former House Majority leader Dick Armey, to label those issues "parochial," a comment that drew a scathing response from the paper.
Hoffman was able to count on an energized base and Republican Party support in the final hours of the contest, but with Scozzafava out of the race, local unions who'd avoided deciding between her and Owens announced their full support for the Democrat.
It was a move that promised a major infusion of ground game resources and volunteers. And Scozzafava herself, whose name remained on the ballot, publicly endorsed Owens.
The race was one where spending by outside groups far outpaced the money that came from the campaigns. The Club for Growth alone spent more than a million dollars on the race - more than Hoffman and Owens combined, and nearly as much as the Democratic and Republican congressional committees poured into the district.
But Democrats weren't the only one to claim victory Tuesday night. Anti-Scozzafava conservatives said the evening had marked a win for their side too.
"(T)he GOP now must recognize it will either lose without conservatives or will win with conservatives," wrote RedState's Erick Erickson. "In 2008, many conservatives sat home instead of voting for John McCain. Now, in NY-23, conservatives rallied and destroyed the Republican candidate the establishment chose …."
He warned the GOP that Hoffman's showing marked a wake-up call for the party establishment, pointing to next year's Florida Senate primary that pits the national leadership's pick, Gov. Charlie Crist, against conservative favorite Marco Rubio.
"So we have demonstrated to the GOP that it must not take conservatives for granted. …. The GOP had better pay attention," Erickson warned. "For all intents and purposes, NY-23 is a trial run for Florida. And in Florida, the conservative candidate is operating inside the GOP. If John Cornyn and the NRSC do not want to see Florida go the way of NY-23, they better stand down."