WASHINGTON, DC - MAY 16: House Financial Institutions and Consumer Credit Subcommittee Chairman Shelley Moore Capito (R-WV) listens to testimony during a hearing on the Dodd-Frank Act and the definition of Systemically Important Financial Institutions on Capitol Hill May 16, 2012 in Washington, DC. The recent announcement by JPMorgan Chase of a $2 billion trading loss loomed large in the hearing as lawmakers heard regulators testify about what makes a bank or institution 'too big to fail.' (Photo by Chip Somodevilla/Getty Images) House Financial Institutions and Consumer Credit Subcommittee Chairman Shelley Moore Capito (R-WV) listens to testimony during a hearing on the Dodd-Frank Act and the definition of Systemically Important Financial Institutions on Capitol Hill May 16, 2012 in Washington, DC. (credit: Chip Somodevilla/Getty Images)

CHARLESTON, W.Va. (AP) — Republican Shelley Moore Capito soundly defeated Democrat Natalie Tennant to win West Virginia’s open U.S. Senate seat Tuesday, a key victory in Republicans’ push to seize a majority from Democrats.

The seven-term congresswoman will become West Virginia’s first female in the Senate, and its first Republican senator in about 55 years. Democratic Sen. Jay Rockefeller is retiring after about three decades.

Capito’s win highlights the shift toward the GOP in a state that has long been Democratic. Capito tied Tennant to President Barack Obama at every turn and West Virginia’s secretary of state apparently wasn’t able to shake it. Obama, who lost all 55 counties in 2012, has horrendous approval ratings in West Virginia.

Portraying herself as a staunch opponent of the president, Capito portrayer herself as a moderate Republican in highly-polarized Washington. She was declared the winner within minutes of polls closing Tuesday.

“We were one of the first states to send a message to President Obama tonight that his policies were on the ballot today,” Capito said during her victory speech in Charleston.

She received close to three out of 10 Democratic votes and almost seven of 10 independent votes, according to preliminary results of an exit poll of 960 voters conducted for The Associated Press and television networks.

Thomas and Patricia Nelson of Hamlin, both registered Democrats, crossed over for Capito.

“Somehow, there’s going to have to be a change,” Thomas Nelson said.

Much of the conversation steered toward Obama and coal.

Both Capito and Tennant voiced opposition of a federal push to curb carbon emissions from coal-fired power plants. Appalachian coal mining advocates fear it would cripple their industry, which already is shrinking.

Tennant pledged to buck the president on energy, gun rights and other issues. She even pretended to cut the power to the White House in a TV ad to prove her coal allegiance.

Capito responded by constantly referencing Tennant’s support for the president’s election in 2008 and 2012. Last month, Tennant told the Charleston Daily Mail editorial board she voted for “the Democrat Party” for president in 2012, adding she was “as angry as everyone else is” at Obama.

Tennant, who will continue her duties as secretary of state, called Capito a “formidable opponent.”

“We fought not because it was easy, but because it was the right thing to do,” Tennant said at her election night party in Charleston.

Tennant painted Capito as overly concerned with helping the wealthy. She said Capito, who sits on the House Financial Services Committee, was Wall Street’s best friend in Congress.

Capito first won her 2nd Congressional District seat in 2000 and was a state lawmaker before that. Her father, Arch Moore, spent 12 years and three terms as the Republican governor in the late 1960s, 1970s and 1980s.

Capito announced her bid for the Senate seat a couple weeks after the November 2012 election, before Rockefeller decided to retire. Tennant entered the race 10 months after Capito, who started with $1.6 million from her House account and maintained a big cash edge all along.

Through mid-October, Capito raised $7 million and spent $7.4 million, compared with $3.3 million raised and $2.5 million spent by Tennant.

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