Massachusetts state Sen. Scott Brown (R) has defeated state Attorney General Martha Coakley (D) in the hotly contested race to fill the late Sen. Edward Kennedy’s (D) seat.With 79 percent of precincts reporting, Brown had 53 percent to Coakley’s 46 percent. Independent candidate Joseph Kennedy (no relation to the late Senator) had 1 percent.Brown’s victory, which is likely to be viewed as one of the biggest political upsets of all time, will strip Senate Democrats of their 60-seat supermajority when Brown is sworn in. Brown’s victory must be certified by the state before the Senate will seat him, a process that will take at least 10 days. Republicans, however, may try to seat Brown right away based on unofficial results.The GOP’s come-from-behind win will no doubt send shock waves through the national Democratic establishment nine and a half months before House and Senate Democrats defend their majorities in the 2010 midterm elections.Brown was considered an underdog at best at the outset of the contest given the Bay State’s heavy Democratic tilt, but his campaign surged over the past week and the final polls showed he had all the momentum heading into Election Day.President Barack Obama made a last-minute trip to campaign for Coakley over the weekend, and national Democrats and their allied groups poured more than $5 million into advertising and other efforts to boost Coakley.But in the end, Coakley couldn’t overcome Brown’s wide lead among independent voters — a key voting bloc that has largely voted for Democrats over the past two election cycles.Stay tuned to RollCall.com for the latest updates.