WASHINGTON – President Obama conceded Wednesday that he suffered “a shellacking” in Tuesday’s election and seemed headed toward a collision with Republican leaders over the administration’s health care initiative as an uneasy realignment of political power began to solidify.

Republicans formed transition teams and released reports outlining their plans, while a somber Obama held a news conference that was a mix of contrition and defiance.

Obama said he was open to compromise with Republican leaders, who picked up at least 60 seats in Tuesday’s historic election, enough to regain control of the U.S. House when Congress opens its new session in January.

Tax cuts, changes in Washington’s culture and elimination of pet spending projects all are issues on which the two sides might reach agreement, Obama said. But beyond a “tweak” or two, the president made plain he would not stand for repeal of a health care law that he views as the crowning achievement of his 22-month tenure.

Rep. John Boehner, R-Ohio, called the law a “monstrosity.” Obama, speaking to reporters in the East Room of the White House, said: “I think we’d be misreading the election if we thought that the American people want to see us for the next two years re-litigate arguments that we had over the last two years.”

The high-stakes confrontation is looming between the president and the reconfigured House of Representatives. House Speaker Nancy Pelosi, D-Calif., will be demoted, with Boehner poised to take her place.

“The American people spoke, and I think it’s pretty clear that the Obama-Pelosi agenda is being rejected by the American people,” Boehner said. “They want the president to change course.”

Rep. Eric Cantor, R-Va., who is expected to become the House’s new majority leader, said the party’s focus will be reviving the economy.

“The first order of business has got to be create jobs,” he said.

But Cantor’s office on Wednesday circulated a 22-page working blueprint for the new Congress in which he explicitly vowed to attack the health care bill on every front, describing it with the pejorative term “ObamaCare.”

“If all of ObamaCare cannot be immediately repealed, then it is my intention to begin repealing it piece by piece, blocking funding for its implementation, and blocking the issuance of the regulations necessary to implement it,” Cantor said in the document. “In short, it is my intention to use every tool at our disposal to achieve full repeal of ObamaCare.”

As the two parties positioned themselves in the new political landscape, results from Tuesday’s elections were still coming in. Sen. Michael Bennet, D-Colo., prevailed in a tight race against Republican Ken Buck, a tea party candidate. That means Republicans have thus far picked up a total of six Senate seats, four short of the number needed to gain the majority.

Senate contests in Alaska and Washington remained too close to call Wednesday. The race in Alaska, which involves write-in candidate Sen. Lisa Murkowski, could take weeks to resolve.

Obama held his news conference after an election that found him on the wrong side of a piece of political history. Less than a dozen House races are still undecided. But based on the results as of Wednesday, the GOP pick-ups represent the largest mid-term gain by either party since 1948.

Much as he insisted the election was not a referendum on him, Obama campaigned as if his name was on the ballot. He crisscrossed the country for his party, painting Republicans as an incompetent, obstructionist and backward-looking force in American politics. Now his agenda is where he hoped it would never be — at least partly in Republican hands.

He offered conciliatory words in his hour-long news conference, hoping to bridge differences that widened over the course of a toxic campaign. Rather than putting forward an agenda reflecting Democratic interests, he said policy must be an amalgam of ideas embraced by both parties.

“So I think what we’re going to need to do, and what the American people want, is for us to mix and match ideas, figure out those areas where we can agree on, move forward on those, disagree without being disagreeable on those areas that we can’t agree on,” Obama said.

In the next few weeks, he said, he plans to hold a meeting with the four leaders of the House and Senate to discuss the tax cuts that are set to expire, among other issues. Aides to the president said he wants to govern from the center. In his news conference, he made his first post-election overture along those lines. He even appeared ready for a deal on the expiring tax cuts.

Throughout the campaign season, Obama criticized Republican insistence on extending all of the Bush tax cuts, which are set to expire this year. His plan was extend them for people who earn less than $250,000, but let them run out for those making more.

Asked Wednesday if he is willing to negotiate on that point, Obama said: “Absolutely.”

Obama also seemed optimistic that he could reach agreement with Republicans on changing the way Washington works, a major theme of his 2008 campaign. He accepted blame for slow progress on this front. And he mentioned the elimination of “earmarks” — pet spending projects approved with minimal oversight — as one potential point of compromise.

The president said: “We were in such a hurry to get things done that we didn’t change how things got done. And I think that frustrated people.”

But it seems doubtful the elections will usher in a period of bipartisan comity. Each party hoped that the other would be the one to yield.

McConnell said he was “determined to stop the agenda Americans have rejected. We will work with the administration when they agree with the people, and confront them when they don’t.”