WASHINGTON - From marauding jihadists in Iraq to pro-Russian separatists in Ukraine and beheadings of Americans in Syria, a world in crisis has fanned perceptions of an overwhelmed U.S. president and contributed to a Republican sweep of U.S. midterm elections. But the slide of public confidence in President Barack Obama and the takeover of U.S. Congress by resurgent Republicans will complicate, though not seriously undermine, U.S. foreign policy that is grappling with wars in the Middle East and Eastern Europe, and a more aggressive China in Asia. Republicans rode to victory with a boost from the widespread view of an Obama White House beset by perpetual crisis. Broadcasts of black-clad Islamic State militants advancing in Syria or medical teams in white hazmat suits grappling with the Ebola epidemic played endlessly on TV news broadcasts, badly damaging Democrats at Tuesday's mid-term elections. Obama's opponents will now wield greater power on Capitol Hill in the final two years of his tenure. But the president will still possess broad constitutional powers to conduct foreign policy and could decide to focus more of his attention abroad, taking his cue from the second terms of past presidents, if Congress stymies his domestic ambitions. Whether he wants to make more of a mark internationally or not, Obama will have a long list of formidable challenges. "The world sees a lame-duck with his authority undermined," said Aaron David Miller, a former Middle East adviser to both Republican and Democratic administrations. "It will be the perception of a diminished president who will have a difficult time sailing the already difficult waters of Washington."

Foreign policy intrudes on midterms Republicans have long accused Obama of weakening America's global leadership by failing to act more forcefully in the world's crises. Obama and his aides have pushed back against critics they say are promoting reckless military action. Having taken over the Senate and increased their majority in the House of Representatives, Republicans will be in a stronger position to push for a harder line in talks between world powers and Iran aimed at curbing its nuclear program and preventing it from developing an atomic bomb, which Tehran denies seeking. With a Nov. 24 deadline looming for a comprehensive deal, Republicans fear that Obama will make too many concessions for easing sanctions that have crippled Iran's economy. He could suspend some sanctions on his own but would eventually need a congressional vote to lift the measures permanently. An accord with Iran after decades of estrangement with the United States would be a big boost to Obama's international legacy, which so far has lacked a signature major success. New York Republican Rep. Peter King said that with his party's control of the Senate, Republicans would be able to retaliate with new legislation if Obama tries to bypass them on Iran. "If he tries to be cute and sneak something through, there may be a backlash," King told Reuters. Another source of continuing friction will be Obama's handling of the battle against Islamic State, which is also known as ISIL and has seized large swathes of Syria and Iraq. Leading Republicans insist that Obama's objective to "degrade and ultimately destroy" Islamic State will fail unless he goes beyond the current bombing campaign and limited assistance to moderate Syrian rebels. On the heels of the mid-term outcome, some are demanding a reversal of Obama's refusal to send more U.S. forces to Iraq, a reflection of his reluctance for large-scale use of U.S. military power, especially in the volatile Middle East. "That seems to me to be physically impossible to stop ISIL without boots on the ground," said Republican Utah Senator Mike Lee, a member of the Senate Armed Services Committee.

At odds over Ukraine and Guantanamo Obama will also likely face Republican pressure for a stronger stand against Russian President Vladimir Putin over Moscow's role in Ukraine, which has sent U.S.-Russian relations to a post-Cold War low. Obama has mobilized European cooperation on sanctions, but many Republicans want tougher measures. Another issue likely to create friction could be the fate of the internationally condemned prison for foreign terrorism suspects at the U.S. Naval Base at Guantanamo Bay in Cuba. Obama inherited the prison from his predecessor, George W. Bush, and has repeatedly vowed, and failed, to close it. Most Republicans vehemently oppose emptying the jail. The Republican takeover of the Senate would seem to cast even further doubt on Obama's ability to shutter it. A Republican Congress, however, may take a more favorable view of a landmark trans-Pacific trade deal that Washington is negotiating. It will be high on the agenda when Obama attends an Asia-Pacific summit in Beijing next week. If Obama is seeking another legacy achievement, he may look to ease the Cold War-era embargo on Cuba after loosening some restrictions in his first term. But Republicans would be expected to oppose such a move.