Republican Scott Brown has pulled off a stunning upset in a special election to fill former Senator Ted Kennedy's seat in Massachusetts.

"Brown led by 52 per cent to 47 percent with all but 3 percent of precincts counted," the Associated Press noted during Brown's victory speech.

MSNBC reported that Coakley called Brown at 9:13 p.m. EST to concede the race.

The race between Brown and Democratic candidate Martha Coakley had been hotly contested in recent weeks as it became apparent that Brown was a legitimate contender who could derail Democrats' super majority in the Senate. Brown has said he wants to see the president's health reform proposals go "back to the drawing board," drawing criticism from leading Democrats who interpret that to mean he wants to see the efforts end.

The White House admitted Obama was "surprised and frustrated" and "not pleased" about the narrow nature of the race, but dismissed the idea that it showed he was out of touch with the angry mood felt by Americans.

"I hope they're paying close attention because tonight the independent voice of Massachusetts has spoken," Brown said at his victory rally. "The voters of this commonwealth defied the odds and the experts. Tonight, the independent majority has delivered a great majority."

Brown held up a copy of Wednesday's Boston Herald, featuring his photo and the cover headline, "He did it." The Senator-elect later boasted that when he spoke to President Obama, he asked, "Mr. President, would you like me to drive the truck down to Washington so you can see it?"

An excited crowd chanted, "Obamacare is dead," "Shock the world," and "Yes, we can," according to The Boston Globe.

"I'm ready to go to Washington without delay," Brown said.

The loss of the seat dissolves the Democrats' supermajority in the U.S. Senate, allowing Republicans to throw up multiple road blocks that will slow Obama's sweeping domestic agenda.

A lackluster campaign by Democratic nominee Coakley, and a fiery insurgent bid by Republican Brown, fanned populist anger at Obama's program and the economic crisis, setting up Brown's stunning upset.

"Tonight, Scott Brown made history by exceeding all expectations and defeating Martha Coakley in the heart of the Democrat Party’s political stronghold," said RNC Chairman Michael Steele in a prepared statement. "I extend my sincere congratulations to Scott, the Brown family, and his team on their tremendous come from behind victory to become the first Republican U.S. Senator from Massachusetts in more than 30 years. His message of lower-taxes, smaller government, and fiscal responsibility clearly resonated with independent-minded voters in Massachusetts who were looking for a solution to decades of failed Democrat leadership."

"It goes without saying that we are disappointed in tonight's result," DNC chairman Tim Kaine responded. "There will be plenty of time to dissect this race and to apply the lessons learned from it those to come this fall - but in the meantime we will continue to work tirelessly on behalf of the America people and we will redouble our efforts to lay out a clear choice for voters this November."

"I wish we were here with other and better news tonight," Coakley said during her concession speech. "I will not forget the fierce determination with which we approached this."

"The President congratulated Senator Brown on his victory and a well-run campaign," White House Press Secretary Robert Gibbs told reporters. "The President told Senator Brown that he looks forward to working with him on the urgent economic challenges facing Massachusetts families and struggling families across our nation. The President thanked Attorney General Coakley for her hard work and urged her to continue her advocacy on behalf of working people."

Both parties spent millions of advertising dollars when it became clear late last week that the race was unexpectedly close, and top Democrats and party workers from outside Massachusetts have been flooding voters with calls.

Brown's triumph holds wider implications for Obama's agenda and political prestige, and complicates his bid to pass items like cap-and-trade climate legislation and immigration reform.

Democrats had in recent weeks discussed how to still pass the package of health reforms without needing another vote in the U.S. Senate. The Brown win leaves Democrats in the unsavory position of needing to convince a majority of the U.S. House to accept the Senate bill, or hammer out a compromise and force it through both chambers before Brown assumed Kennedy's seat.

"I think you can make a pretty good argument that health care might be dead," Democratic congressman Anthony Weiner told MSNBC television.

"That seat, held for nearly half a century by Mr. Kennedy, the liberal lion of the Senate, will now be held by a Republican who has said he supports waterboarding as an interrogation technique for terrorism suspects; opposes a federal cap-and-trade program to reduce carbon emissions; and opposes a path to citizenship for illegal immigrants unless they leave the country," The New York Times reported. "It was a sharp swing of the pendulum, but even Democratic voters said they wanted the Obama administration to change direction."

Massachusetts Secretary of State William Galvin has said he will not slow the certification of Brown's victory.

With AFP.