Rocky road for Obama with Republicans in charge of U.S. Congress WASHINGTON (Reuters) - President Barack Obama faced a political rebuke and a curb on his policy ambitions on Wednesday after Republicans seized control of the U.S. Senate and captured their biggest majority in the House of Representatives since Harry Truman's presidency more than 60 years ago. Tuesday's midterm elections gave Republicans control of both houses of Congress for the first time since elections in 2006. Obama, who has lurched from crisis to crisis and whose unpopularity made him unwelcome to many fellow Democrats running for office, scheduled a news conference for 2:50 p.m. EST (1950 GMT) on Wednesday. He invited Democratic and Republican leaders of Congress to the White House on Friday to take stock of the new political landscape. It was "a pretty ugly night" for Democrats, said Representative Steve Israel, chairman of the Democratic Congressional Campaign Committee, speaking on MSNBC. When the new Congress convenes in January, Republicans will be armed with their biggest majority in the House since the Democrat Truman's first term in the late 1940s. With some races yet to be decided, NBC News projected Republicans would win at least 244 seats in the 435-seat chamber. The Republican takeover will force Obama to scale back his ambitions to either executive actions that do not require legislative approval, or items that might gain bipartisan support, such as trade agreements and tax reform. It also will test his ability to compromise with newly empowered political opponents who have been resisting his legislative agenda since he was first elected in 2008. Americans elected him to a second and final four-year term in 2012. In stock market reaction to the results, the energy sector gained on bets that new legislative measures could be favorable. The S&P Energy sector rose more than 1.5 percent on hopes Republican control of the Senate will lead to reform of crude and natural gas export laws and motivate the Obama administration to include those energy exports in new, or broader, trade agreements. Republicans have pressed the president to approve the Keystone XL pipeline carrying oil from Canada. New Jersey Governor Chris Christie, a possible presidential candidate in 2016 who campaigned for fellow Republicans around the country, said the Senate results put the burden on Obama. "We need to get things done ... and put things on the president's desk and make the president make some decisions," Christie said on "CBS This Morning." He cited tax reform, a national energy policy and job stimulation as pressing needs. The shift in the Senate also could prompt a White House staff turnover as some exhausted members of the Obama team consider departing in favor of fresh legs. {ID:nL1N0SS0FC] Before the election results, the White House had signaled no major changes. Officials said Obama would seek common ground with Congress in such areas as trade and infrastructure. A one-term senator before he became president, Obama has often been faulted for not developing closer relations with lawmakers. He will find one familiar face in a powerful new position. Republican Senator Mitch McConnell of Kentucky, who won a tough re-election battle against Democrat Alison Lundergan Grimes, will replace Democrat Harry Reid as Senate majority leader. Reid has been one of Obama's top political allies and helped steer the president's signature healthcare law through the Senate in 2010. Some things don't change after tonight. I don't expect the president to wake up tomorrow and view the world any differently than he did when he woke up this morning. He knows I won't either. But we do have an obligation to work together on issues where we can agree," McConnell said in his victory speech in Louisville. In Tuesday's rout, Republicans won in places where Democrats were favored, pulled out victories where the going was tough and swept a number of governors' races in states where Democrats were favored, including Obama's home state of Illinois. Republicans needed six seats to win control of the 100-member Senate. By early on Wednesday, Republican candidates had picked up seven Democratic seats: Arkansas, Colorado, Iowa, Montana, North Carolina, South Dakota and West Virginia. Democrats had dominated Republicans in the Senate, 53-45 with two independents, going into the election but Republicans will now outnumber them 52-45 with two independents. Louisiana's U.S. Senate race will be decided in a Dec. 6 runoff. In the House, Republicans had held a 233-199 advantage before Tuesday's vote. NBC News projected they would hold at least 244 seats and as many as 249 seats. The last time Republicans controlled both houses of Congress under a Democratic president was 1995-97 during Bill Clinton's administration. Once the euphoria of their victory ebbs, Republicans will be under pressure to show Americans they are capable of governing after drawing scorn a year ago for shutting down the government in a budget fight. That will be a factor in their ambitions to take back the White House in 2016. Partisan battles could erupt over immigration reform, with Obama poised to issue executive actions by year's end to defer deportations of some undocumented immigrants. Additional reporting by Jeff Mason, Susan Heavey, Tim Ryan and Ian Simpson in Washington and Ryan Vlastelica in New York; Marti Maguire in Raleigh, North Carolina; David Beasley in Atlanta; Steve Bittenbender in Louisville, Kentucky; Barbara Liston in Orlando, Bill Cotterell in Tallahassee and Zachary Fagenson in Miami Beach; Colleen Jenkins in Winston-Salem, North Carolina; Jonathan Kaminsky in New Orleans; Editing by Frances Kerry and Howard Goller