WASHINGTON – The big Republican gains in Congress could make it harder for President Barack Obama to keep his pledge to start bringing U.S. troops home from Afghanistan by next summer and dim prospects for several of his administration's centerpiece military and diplomatic initiatives.
The GOP's victories seem likely to derail congressional efforts to repeal the "don't ask, don't tell" ban on gays serving openly in the military, thwart efforts to curb the growth of Pentagon spending and frustrate hopes for quick ratification of a nuclear arms control agreement with Russia.
More Republicans in Washington may also mean trouble for Obama's efforts to improve U.S. relations with Iran and Cuba and restart disarmament talks with North Korea.
More than 30 tea party candidates won election to Congress, according to an analysis by The Associated Press, enough to affect some policy decisions. Some haven't staked out clear national security priorities, while others are libertarians or isolationists who could split the GOP with debates over the U.S. commitment to shaping events abroad.
Tea party hero Rand Paul, now a senator-elect from Kentucky, has said the greatest threat to U.S. national security is a lack of border control. On his website, Paul also says that "when we must fight, we declare war as the Constitution mandates and we fight to win." Congress has not formally declared war since World War II.
If the Republicans can avoid internal divisions, they will be able to slow some Obama programs or policies and kill others.
On Afghanistan, some Republicans say they will increase pressure on Obama to stick with a war plan they generally support, using the bully pulpit of congressional hearings this spring.
They will argue that Obama's plan to begin withdrawing forces in July 2011 is arbitrary and that war commanders should not be asked to yank forces prematurely.
"If we see the White House beginning to discuss withdrawing, and the conditions aren't right on the ground, you're going to see us talk about the importance of keeping focused," said Adam Kinzinger, a Republican and former Air Force pilot who won a House seat in Illinois with tea party support.
The arms control treaty called New START is one of Obama's top foreign policy achievements, but Republicans have held it up in the Senate and Obama is now trying to speed its passage before the new, more Republican, Senate arrives.
On Thursday, Obama used remarks during a Cabinet meeting to urge the Senate to ratify the treaty in the lame-duck session that starts Nov. 15.
"I am hopeful that we can get that done before we leave and send a strong signal to Russia that we are serious about reducing nuclear arsenals, but also send a signal to the world that we're serious about nonproliferation," Obama said.
Republican Senate leader Mitch McConnell responded that he didn't think there will be enough time.
Even with majorities in both houses of Congress, Democrats did not give the White House what it sought — repeal of the "don't ask, don't tell" ban on gays serving openly in the military. Republicans have even less inclination to end the ban now.
Obama said Wednesday that he considers the ban unjust and said there is still time to repeal it before the new Congress arrives.
"This should not be a partisan issue," he said. "You've got a sizable portion of the American people squarely behind the notion that folks who are willing to serve on our behalf should be treated fairly and equally."
But some powerful Republicans oppose repeal, and given the election results, the effort is probably dead for the near future.
"I don't think it's going to go anywhere" in that session, said Rep. Duncan Hunter, R-Calif., who sits on the House Armed Services Committee. He noted that there was opposition among both Republican and Democratic colleagues.
The new Republican-controlled House will also put existing White House defense and foreign policies under a microscope.
Rep. Howard "Buck" McKeon, R-Calif., in line to become chairman of the House Armed Services Committee, promised new oversight and investigation of Obama's Afghanistan strategy, among other things.
"We're not going to be looking for gotcha things," McKeon told The Associated Press. "We're just going to look at things we should be doing and are they doing it."
Like a number of other Republican lawmakers, McKeon strongly supported Obama's decision to send an additional 30,000 troops to Afghanistan this year, but he has also called Obama a "reluctant wartime president" for linking the troop increase with a date for the start of withdrawal.
McKeon said his panel wants to hear directly from the top U.S. commander in Afghanistan, Gen. David Petraeus, this spring. Petraeus has not testified to Congress since taking the job last summer, in part because Democrats were not eager to draw attention to an unpopular war.
A CNN/Opinion Research poll last month found 58 percent of Americans oppose the war, which is now in its 10th year and has cost more 1,200 American lives and $300 billion.
Democrats are already looking toward the presidential election in 2012, and there is strong support among activists for Obama to begin the pullout on schedule.
Many Republicans argue that the exit plan has only raised doubts among U.S. allies while encouraging the Taliban to fight harder, in anticipation of a pullout.
Obama says his date for starting withdrawal is a reminder to everyone that the war cannot run indefinitely, and that he will take security conditions into account in deciding whether to bring any forces home.
"This date has proven problematic from the get-go, and it's going to prove even more problematic" with Republicans controlling the House, said Juan C. Zarate, a deputy national security adviser under President George W. Bush.
"Republicans are going to want to hold the president's feet to the fire and show we are not cutting and running," said Zarate, now at the Center for Strategic and International Studies.
Troop increases and withdrawals are almost entirely the prerogative of the commander in chief, like nearly every other major decision about the management of the war. What Congress can do is make things easier or much harder for the president and hold out the threat of funding cuts for decisions it does not like.
"I still think he is in the driver's seat because I don't believe he was ever going to make actual decisions on troop drawdown plans based primarily on domestic politics," said Michael O'Hanlon, a defense analyst at the Brookings Institution.