In a fierce fight to keep his job in deep-blue Massachusetts, the freshman GOP senator is shunning tea party Republicans who helped send him to Washington and embracing the same populist fervor that’s made Warren, his likely Democratic rival, a hero among liberals.

Brown was the only Republican to back President Barack Obama’s pick for the consumer watchdog agency that Warren spearheaded. He was one of the first to jump on the bandwagon against congressional insider trading. And after he helped pass a piece of Obama’s jobs plan, Brown made sure he was standing by the president for the photo op.

Brown’s practically written the talking points for Democrats in this week’s showdown with Republicans over extending the payroll tax cut, one of Obama’s year-end legislative priorities…

“This is far from a profile in courage. It is pure pandering by a vulnerable incumbent who is already losing in the polls,” said Matt Canter, a spokesman for the Democratic Senatorial Campaign Committee. “Voters in Massachusetts have already figured out that they can’t count on Scott Brown. He is just the typical politician who will say or do anything to get elected. Voters up there have a nickname for this kind of thing — they call it Mitt Romney.”