WASHINGTON -- The Republicans' loss of their lock on Congress leaves President Bush facing a bleak outlook in the remaining two years of his term, with little chance to win approval of his priorities or salvage key parts of his legacy without significant fights.
From the Iraq war to taxes, immigration and the future of Social Security, analysts said, the president will have to adapt to a new power dynamic on Capitol Hill, where legislative battles will be routine and gridlock chronic.
"He really does become a lame duck," said historian George C. Edwards III of Texas A & M University. "It's going to be a very difficult time for him to pass signature legislation, and he's never shown much interest in [compromising] on his proposals."
Bush has "a decision to make as to whether or not he's going to have two years of confrontation or whether he's going to have two years of an administration that tries to work with our side; whether he's going to have a failed administration or try to have some successes," said Rep. Steny H. Hoyer of Southern Maryland, the second-ranking House Democrat, who could move up to Democratic leader.
The White House will have to contend with more rigorous oversight from Democrats on Bush's handling of Iraq, the Medicare prescription drug benefit and environmental regulation, among other topics.
Bush has laid out an ambitious to-do list, much of it at risk with Democrats in control of the House next year.
On Iraq, Democrats are calling for a gradual drawdown of U.S. troops starting this year - an idea Bush has repeatedly rejected. With some Republicans joining the call for a fresh debate on the war, Bush may need a new timetable.
An independent commission, co-chaired by Republican James A. Baker III, a former secretary of state, and Democrat Lee H. Hamilton, a former Indiana congressman, is expected to call for major shifts in Iraq, and Bush hinted in the run-up to yesterday's balloting that he would consider them.
"The agenda and his legacy and the nature of this election is really wrapped up in Iraq," said George Washington University's Stephen Hess, a specialist on the presidency.
"They've got to make some very substantial changes if there's any chance for another Republican candidate to be elected [president] in 2008."
Bush's goal of extending his income and investment tax cuts, which are set to expire by 2011, could be in jeopardy.
Democrats oppose the lion's share of the package, with the possible exception of the reduction for the lowest wage earners and targeted cuts such as the credit for children, and would be all but certain to block its renewal.
Bush, who has resisted raising the minimum wage, will be hard-pressed to block such an increase now, with some Republicans ready to join Democrats in supporting it.
The White House has said that Bush wants to overhaul major federal programs, including Social Security and Medicare.
But given his failure last year to make progress on his Social Security proposal, including partial privatization of the federal retirement program, there is little reason to believe he will be able to persuade the new Congress to go along.
His free-trade agenda is also likely to stall next summer, with the expiration of his power to send trade pacts to Congress for a quick up-or-down vote - known as "fast track" authority.
Bush is already facing the classic challenges of a second-term president in the latter half of his term - waning interest in his agenda, an exodus of top-tier officials, a focus on his would-be successors - now made more difficult by his party's electoral losses.
"It's going to make it more difficult to govern," former Republican Rep. J. C. Watts of Oklahoma told CNN. "It's going to change the landscape."
Prospects for Bush's signature immigration plan are dim after a campaign in which many Republicans ran on their opposition to it, branding the proposal amnesty for illegal immigrants.
While White House aides say that Bush wants to reach out to like-minded Democrats, such cooperation is unlikely, according to analysts, after such a contentious election.
"By this time, any administration recognizes what's doable, and what's not doable, and if it's doable, they've done it by now," Hess said.
That doesn't mean that Bush has lost all power, but it suggests that the president might be left reacting to Congress rather than driving what happens there.
Having spent the first six years of his presidency largely avoiding the veto - much to the chagrin of conservatives who wished he would use it to curb excessive spending - Bush might employ it more often now.
Also, the president might face one of his steepest challenges from lawmakers in his own party, who now might eschew compromises that would give Bush marginal victories on his top goals.
Republicans are "certainly going to be concerned about 2008 - much more concerned about that than about Bush's legacy," Edwards said.
Bipartisanship - virtually absent from Washington during the last four years - is an even more remote possibility in the current circumstances.
"You're going to have to start over with a new president and even presumably a Congress, where there's an opportunity to cooperate," Hess said. "Until then, we're going to have two years of gridlock, two years of getting ready and preparing for the next go-round."