Washington — Washington US Senator Patty Murray won a narrow victory Thursday, surviving voters' backlash against Democrats and ensuring that US President Barack Obama's party will keep 53 seats in the 100-seat chamber.Murray, for whom Obama had campaigned, claimed victory over Republican Dino Rossi after three days of tallying, preserves breathing room for the Senate's shrunken Democratic majority. Republicans made inroads there Tuesday and took control of the House of Representatives for the rest of Obama's first term.RELATED:Obama calls for bipartisan White House meetingCantor to be highest-ranked Jewish House member everAlaska remains the only remaining undecided Senate race.Murray's win was secured Thursday as tallies pushed her lead to about 46,000 votes out of more than 1.8 million counted, or about 51 percent to 49 percent. About three-quarters of the expected ballots had been counted in unofficial returns.Hundreds of thousands of ballots still await processing, but an Associated Press analysis determined Murray's lead would be insurmountable.At a Thursday night news conference, Murray thanked Rossi and his family, saying he had been gracious in defeat. Murray said her priorities in a fourth term will include securing tax cuts for the middle class and helping the Boeing Company win a lucrative Air Force refueling tanker contract. "Now we have to get to work," Murray said. "I want to make sure Washington state has what it needs to get its economy back on its feet."Rossi conceded defeat in a statement issued Thursday evening. He also called on the new-look Congress to focus on the economy and strive for cooperation.Murray's campaign offered a strong defense of her ability to win federal spending, even in a year when economic jitters threatened to derail that traditional strength for sitting senators. The list of projects she touted was seemingly endless: Bridges, highways, veterans' hospitals, dams, port construction and more.Murray also sought to paint Rossi as a friend of big business, pointing to his call to repeal the Democrats' new Wall Street regulations.