The Republican victory wave might end up even larger once all the votes are counted.
Already Wednesday, Republicans seized control of the Senate with a minimum of 52 seats, added to their majority in the House, and picked up governorships in deep-blue Democratic states such as Illinois, Maryland and Massachusetts.
And with races in Alaska and Virginia still not settled and a runoff in Louisiana in December — all seats now held by Democrats — Republicans could add to their new Senate majority.
“The Republican Party is back with youth, with diversity, with women, and we’ve got a long way to go,” said Rep. Greg Walden of Oregon, the House Republican campaign chairman, who called the gains “historic” and a referendum on President Barack Obama. “We’re back to a majority as big as any of us have seen in our lifetime.”
Obama and incoming Senate Majority Leader Mitch McConnell pledged to try to turn divided government into a force for good rather than gridlock but also warned of veto showdowns.
Trade legislation loomed as one possibility for quick compromise, and immigration as an early irritant.
“There is no doubt that Republicans had a good night,” the president said at the White House.
To voters who handed the GOP control of Congress, he said, “I hear you. … It’s time for us to take care of business.”
He cited construction of roads, bridges and other facilities as one area ripe for cooperation, and trade as another.
At the same time, he noted, “Congress will pass some bills I cannot sign. I’m pretty sure I will take some actions that some in Congress will not like.”
Republicans held all their own Senate seats Tuesday night and swept Democratic-held seats in Arkansas, Colorado, Iowa, Montana, North Carolina, South Dakota and West Virginia, enough to gain the majority for the first time since 2007.
In Alaska, Republican Senate candidate Dan Sullivan had a sizable lead over incumbent Democratic Sen. Mark Begich. But with votes yet to be counted, Sullivan hadn’t declared victory.
In Louisiana, Democratic Sen. Mary Landrieu won a plurality in a multicandidate field but fell short of the majority needed to win outright under the state’s election rules. Now she will face Republican Rep. Bill Cassidy in a runoff Dec. 6. Polls suggest that the Republican votes will coalesce and she will lose.
And in Virginia, the Senate contest remained undecided on Wednesday, with Democratic incumbent Sen. Mark Warner leading Republican Ed Gillespie, a former Republican National Committee chairman, by fewer than 14,000 votes out of more than 2 million cast. Gillespie had not yet conceded.
“There’s no doubt it was a very rough night for Democrats,” Rep. Chris Van Hollen, D-Md., told CNN. “Clearly, the country is frustrated with the gridlock in Congress. … And yet somehow that obstruction on popular issues ricocheted onto the president, and we saw the results last night.”
Democratic efforts to offset the Republican momentum with gains of their own failed. In the most visible contest, McConnell easily beat Democrat Alison Lundergan Grimes in Kentucky and will now become Senate majority leader.
Democrats had one bright spot: holding New Hampshire, where Sen. Jeanne Shaheen turned back a strong challenge from former Massachusetts Sen. Scott Brown.
Republicans expanded their majority in the House, gaining at least 10 seats and looking for their biggest majority in nearly a century.
Democratic incumbents fell, including Reps. Nick Rahall of West Virginia and Joe Garcia of Florida.
In California, Carl DeMaio, one of two openly gay Republicans running competitive races for the House, had a narrow lead over Democratic Rep. Scott Peters.
And in Utah, Mia Love became the first Haitian-American and black woman to win a congressional seat for the Republicans.
Democrats gained just one seat from the Republicans, with Gwen Graham, the daughter of former Sen. Bob Graham, ousting Republican Rep. Steve Southerland in a north Florida district.
Although there were still undecided contests, Republicans were on track to have their largest majority since they held 270 seats in the 71st Congress, between 1929 and 1930, House Speaker John Boehner’s office said.
In gubernatorial races, Republicans ousted Democrats in Arkansas, where Rep. Asa Hutchinson beat out Blue Dog Democrat Mike Ross, a congressman; in Maryland, where Republican businessman Larry Hogan upset Democratic Lt. Gov. Anthony Brown; and in Massachusetts, where Republican Charlie Baker defeated state Attorney General Martha Coakley, becoming the first Republican governor in Massachusetts since Mitt Romney.
Republicans also took Obama’s home state of Illinois, where Obama had campaigned in the waning days for Democratic Gov. Pat Quinn, who lost to Republican Bruce Rauner.
This report includes material from The Associated Press.