Updated

Sen. Scott Brown's last-minute support for President Obama's sweeping financial overhaul legislation has put him in the crosshairs of Tea Party activists who have sharply criticized the bill and could dim his re-election hopes for 2012.

Brown announced Monday he would support the regulatory overhaul despite initial misgivings, joining fellow New England Republican Sens. Olympia Snowe and Susan Collins, a triple play that appears to give Democrats the required 60 votes to overcome procedural hurdles facing the legislation.

The Greater Boston Tea Party said it was "greatly disappointed" in Brown's announcement.

"After weeks of debate and a thorough investigation of the bill and its possible effects on the economy, small businesses, community banks and consumers, we are at a loss as to what redeeming qualities Sen. Brown found in the bill worthy of support," the group said in a press release.

"Scott Brown promised in the fall of 2009 to stand up for free markets and constitutional principles," the group added. "A yes vote on this bill – a bill that disregards Fannie Mae and Freddie Mac, greatly expands executive authority and reach, creates a perpetual and permanent bail-out system and fosters the creation of even more bureaucracy – defies the commitment he made to thousands of activists and donors across the nation who swept him to office in January in one of the biggest political upsets of all time."

The group said if Brown wants its continued support, "he must consider how legislation he supports upholds" constitutional principles of limited government, free markets and individual liberty.

Brown's office did not return messages seeking comment.

Like Snowe, Brown won concessions in the bill before giving his blessing, most notably the subtraction of a new $19 billion tax on large financial institutions. He said Monday that the legislation "is a better bill than it was when this whole process started."

"While it isn't perfect, I expect to support the bill when it comes up for a vote," he said in a statement. "It includes safeguards to help prevent another financial meltdown, ensures that consumers are protected and it is paid for without new taxes."

Christen Varley, president of the Greater Boston Tea Party, told the Boston Herald that Brown may not be able to count on the Tea Party support in 2012 that helped propel him to his improbable upset in January to win the seat long held by the late Ted Kennedy.

"I'm looking at the 'Scott Brown' bumper sticker on the back of my car and having serious doubts (about him)," Varley said. "We'll all have to independently make a decision in 2012 about whether we'll support him again."