Former Massachusetts Treasurer Joe Malone said Thursday he expects to run against an incumbent congressional Democrat this fall, part of a wave of political recalibrations occurring nationally after Republican Scott Brown's upset win in the special election to replace Sen. Edward M. Kennedy.

BOSTON — Former Massachusetts Treasurer Joe Malone said Thursday he expects to run against an incumbent congressional Democrat this fall, part of a wave of political recalibrations occurring nationally after Republican Scott Brown's upset win in the special election to replace Sen. Edward M. Kennedy.

California Sen. Barbara Boxer, a liberal Democrat facing a re-election challenge, declared "every state is in play now." The anti-spending group Club for Growth said it's trying to recruit conservative Rep. Mike Pence to challenge Democratic Sen. Evan Bayh in Indiana.

Congressional Republicans see House seats in Arkansas, New York, Michigan and Ohio in play, raising their hopes for winning back majority control they lost in 2006.

"The message of Massachusetts is clear: No Democrat is safe," said Paul Lindsay, spokesman for the GOP committee charged with electing Republican House members. "We're already seeing the ripple effects."

The GOP also is hoping to entice former Maryland Gov. Robert Erlich into a rematch against incumbent Democratic Gov. Martin O'Malley.

Tim Murtaugh, spokesman for the Republican Governors Association, said Brown's win "helps us tremendously with fundraising, because people say, 'My gosh, if we can win a Senate seat in Massachusetts of all places, we can win anywhere.' It also helps with candidate recruitment."

Brown's victory cost President Barack Obama not just the Democratic Senate supermajority he was counting on to pass his health care overhaul, it also laid bare unrest among pivotal independents, who helped him win in 2008 but abandoned Obama in droves the day before the first anniversary of his inauguration.

Brown rode a wave of populist, anti-government sentiment to claim a seat the Democrats had held in true-blue Massachusetts for over a half-century. The Republican won across Cape Cod, where Malone is planning to run against Rep. William Delahunt, D-Mass.

Brown even claimed the Barnstable precinct where Kennedy voted and the family has its famed compound in Hyannis Port.

"I can't tell you how many people have said to me, 'I had no idea my neighbor felt the same way I do, or my kids were seeing things occurring that were troubling them,'" said Malone, a Republican. "It's a feeling that, 'If we all put our minds to it, we can be in charge as opposed to the politicians.'"

The Senate will have 57 Democrats, two independents who vote with them and 41 Republicans once Brown is sworn in. At least 36 seats are up for election this fall.

Six Republicans are vying for the chance to compete against Democratic leader Harry Reid in Nevada, where polls show him trailing some of those potential rivals. The GOP also is targeting seats in Colorado, Delaware and Illinois, filled with appointees named after Obama was elected or filled out his administration.

Boxer's seat would be the most symbolic for the GOP since, likely Kennedy, she is a liberal figurehead representing a generally liberal state.

Brian Walsh, spokesman for the National Republican Senatorial Committee, said it's too soon to speculate just how many incumbent Senate Democrats might be vulnerable. "If you are someone like Evan Bayh, you voted for the health care bill, stimulus package, you have to wonder," Walsh said.

Democrats control the House by a margin of 256-178 with one vacancy. They could see double-digit losses this fall, a common trend for the party in power, as happened when Democrats last lost control in 1994.

Republicans would have to pick up a net 39 seats to take control of the House, but far more Democratic seats are vulnerable than Republican ones. About two dozen Democratic districts are especially ripe for a switch, compared with about a dozen GOP districts.

In New York's 1st Congressional District, for example, a recent poll in the far eastern Long Island battleground showed Democratic incumbent Tim Bishop leading one of his Republican opponents by the narrow margin of 47 percent to 45 percent.

"I don't think Democrats are going to lose the House," said Rep. Chris Van Hollen of Maryland, who heads the House Democrats' election committee. "The scenario of 1994 is just wrong for a number of reasons," he said, citing fewer Democratic retirements as one of them.

Thirty-seven states are also electing governors this year. Democrats have a 26-24 majority after losing the governor's office in Virginia and New Jersey last fall.

"Our candidates are pretty much set for 2010. I don't expect any movement," said Nathan Daschle, head of the Democratic Governors Association. "I don't think what happened in Massachusetts changes that."

In Massachusetts, Democratic Gov. Deval Patrick sent reassuring e-mails to his supporters and called a news conference with reporters about whether he will continue to seek re-election this fall in the wake of Brown's upset victory Tuesday.

Patrick has dismal poll numbers, and some fellow Democrats suspect Obama may encourage him not to seek re-election or try to lure him away with an administration job. A loss would create the unsavory story line of a fellow black chief executive, with Chicago roots, getting defeated after a campaign run by the same people who put Obama in office.

"That's my decision, not his," Patrick said this week. "I think he knows that."