In a major setback to President Barack Obama’s domestic agenda, including health care reform, as he completes a year in office, a Republican has won a US Senate seat formerly held by liberal Democrat Ted Kennedy.

With 89 per cent of the results counted in Tuesday’s special election, Scott Brown, a Massachusetts state senator, had 52 per cent of the vote to 47 per cent for state Attorney General Martha Coakley, the Democratic contender.

Independent candidate Joseph Kennedy, a libertarian who is not related to the Kennedy political family of Massachusetts, had 1 per cent.

With defeat staring her in the face, Coakley called Brown to concede the election to replace Senator Ted Kennedy, known as the “liberal lion” of the Senate who made health care reform the centrepiece of his nearly 47-year Senate career. Kennedy died of brain cancer in August.

Brown’s victory over Coakley strips Democrats of the 60-seat Senate supermajority needed to overcome Republican filibusters against future Senate action on a broad range of White House priorities.

Until recently, Brown was underfunded and unknown statewide. In addition, no Republican has won a US Senate race in Massachusetts since 1972, and Democrats control the governorship, both houses of the state legislature, and the state’s entire congressional delegation.

Obama has been both “surprised and frustrated” by the race, White House Press Secretary Robert Gibbs said Tuesday.

Considering the high stakes, Obama and former President Bill Clinton hit the campaign trail over the past three days in an attempt to save Coakley’s campaign, which observers say has been hampered by complacency and missteps.

Obama crushed Republican presidential nominee John McCain in Massachusetts in 2008, beating the Republican presidential nominee by 26 points.

“If you were fired up in the last election, I need you more fired up in this election,” Obama urged a crowd at a Coakley campaign rally on Sunday.

Brown, who has trumpeted his 30 years of service in the National Guard, promised at a rally Sunday that, if elected, he would back tax cuts and be tougher on terrorists than Coakley. He also repeated a pledge to oppose Obama’s health care reform effort.

Faced with Coakley’s defeat, Democrats are trying to figure out if they could pass health care reform without that crucial 60th Senate vote.

One option is to pass a final health care bill before Brown is seated, a difficult proposition as House and Senate Democrats would have to reach a deal to meld their bills and pass them in the next couple of weeks.

Another option is to push House Democrats to pass the Senate’s health care bill as currently written. Doing so would prevent the plan from having to be taken up by the Senate again.

A third option would be for Democrats to revisit the idea of trying to push health care through the Senate with only 51 votes -- a simple majority -- through a tedious long drawn process known as reconciliation.

More In: International | News