Republicans have seized a majority in the U.S. Senate from President Barack Obama's party by defeating Democrats in at least seven key states in midterm elections whose results reflected voter discontent.
Republicans also strengthened their grip on the House of Representatives in the balloting on November 4, giving the party control over both chambers of the U.S. Congress for the first time since elections in 2006.
Democrats also lost a series of governors' races, as Republicans held on to populous states including Florida, Michigan, and Ohio and scored upsets in traditional Democratic strongholds such as Maryland, Massachusetts, and Illinois -- Obama's home state.
The loss of a majority in the U.S. upper house will limit Obama's political influence and make it harder for him to get laws passed in his last two years in office.
But Republicans, who who drew criticism for shutting down the government in a budget standoff a year ago, will be under pressure to perform ahead of a 2016 presidential election in which they hope to regain the White House after eight years under Obama.
The Republican Party had needed to take at least six seats held by Democrats to win control of the 100-member Senate.
Republican wins had been almost assured in West Virginia, Montana, and South Dakota after longtime Democratic incumbents retired, but Republicans also defeated Democratic incumbents in Arkansas, Colorado, and North Carolina and won a Democratic-held seat in Iowa left open by a retirement.
Republican candidates also held off challengers for Senate seats in Kentucky, Georgia, and Kansas.
Senate Republican Leader Mitch McConnell, who was reelected in a tough battle in Kentucky, will replace Democrat Harry Reid as the Senate majority leader when the new Congress convenes in January.
Reid has been a key ally of Obama and helped him steer a fiercely debated health-care law that is one of the president's main achievements through the Senate in 2010.
Reid congratulated McConnell on the victory and said that voters want both parties to work together.
McConnell said in his victory speech that it is time for the United States to “go in a new direction" but added, "We do have an obligation to work together on issues where we can agree."
In Louisiana, a close Senate race has gone to a runoff vote on December 6.
A late vote count also was seen as a possibility in a Senate race in Alaska.
Political analysts say a Republican-controlled Congress will be an aggravation to Obama, who is barred from seeking a third term in 2016.
But it remains unclear how much it will change the government.
Obama has the power to veto legislation, and Senate Democrats can use the filibuster to thwart Republican initiatives -- just as Republicans did to Democrats for years.
Voters across the United States cast ballots for 36 of the Senate's 100 members, all 435 members of the House of Representatives, and for the governors of 36 states.
Incumbent Republican governors were reelected in South Carolina, Ohio, and Tennessee, and a Republican beat out a Democrat in Texas.
In Pennsylvania, however, Republican Tom Corbett became the first incumbent governor in his state's modern history to fail to win a second term, losing to Democrat Tom Wolf.
Democratic Governor Andrew Cuomo was the projected winner in New York.