Republican candidates won enough seats in Tuesday's U.S. congressional elections to capture control of the Senate.
Democrats had held 55 of the Senate's 100 seats, but Republicans gained at least seven of them with wins in Arkansas, Colorado, Iowa, Montana, North Carolina, South Dakota and West Virginia.
A third of the Senate was up for reelection Tuesday, including the Kentucky seat held by Senate Republican leader Mitch McConnell. He earned a sixth term in office.
To become Senate majority leader
McConnell beat his Democratic rival, Alison Lundergan Grimes. It was an ugly race, with both sides struggling to outspend the other, and polls showing Grimes leading McConnell as late as last week.
“She earned a lot of votes, and she earned my respect," McConnell said late Tuesday. "It took a lot of guts to take on a race like this. Because of the business we're in, it also meant she'd take some heat. I admire her willingness to step into the arena and fight as hard as she did.”
However, he also told supporters that the election was not about him or his opponent.
“It was about a government that people no longer trust to carry out its most basic duties, to keep them safe, to protect the border, to provide dignified and quality care for our veterans, a government that can't be trusted to do the basic things because it's too busy focusing on things it shouldn't be focused on at all," McConnell said.
With Republicans in control, McConnell will become Senate majority leader. He will have the authority to decide which bills to bring up for a vote.
President Barack Obama said Senate Democrats faced what could be the toughest races since 1958, when Republicans lost 13 Senate seats under then-President Dwight Eisenhower.
Republicans also expanded their solid majority in the House of Representatives, giving them full control of Congress during Obama's final two years in office.
Given Obama's low approval ratings, numerous Democratic officeholders declined to invite the president to campaign for them, and often cited instances in which they disagreed with him, such as on health care or energy issues.
With control of Congress, Republicans could raise new disputes with Obama over his signature legislative achievement, health care reform, which has allowed millions of people to secure insurance coverage they could not previously afford.
Many Republicans view it as excessive government involvement in people's health care and call for repeal of the law.
Attacks on Obama
Republicans also have attacked Obama's handling of the Ebola crisis and called for approval of an oil pipeline from Canada through the central U.S., and a curb on government regulation of businesses.
Some opposition lawmakers have also disputed the president's handling of Russia's intervention in Ukraine and U.S. airstrikes against Islamic State militants in Iraq and Syria.
In Arkansas, U.S. television networks project that Republican Tom Cotton unseated two-term Democratic Senator Mark Pryor. In North Carolina, first term Democrat Kay Hagen was narrowly defeated by Tom Tillis, a state legislative leader.
Shelley Moore Capito became the first Republican elected to the Senate from West Virginia in more than 50 years. And in South Dakota, Mike Rounds, a former Republican governor, won a Senate seat that was held by a Democrat.
Democrats held onto a seat in New Hampshire as Jeanne Shaheen defeated Republican challenger Scott Brown, a former senator from neighboring Massachusetts. Democrats also held onto seats in Michigan, Delaware and Minnesota.
In Louisiana, Democrat Mary Landrieu will face Republican Bill Cassidy in a December runoff, since neither won a majority of the votes.
Landrieu challenged her rival to a series of debates on the issues.
“And I suggest that some of these issues be education, number one, jobs and our economy, Social Security and Medicare, health care, energy and the environment, and yes, international affairs and trade. These are the critical issues for our state," Landrieu said.
Republicans avoided a runoff in Georgia, where David Perdue beat Democrat Michelle Nunn by a comfortable margin.
Attention will now shift to Washington, as the new Congress is sworn in, in January.
Some Republicans have promised that with a majority in both houses, they will work to repeal the president's health care law and challenge him on immigration and other issues.
VOA's Mike O'Sullivan contributed to this article.