WASHINGTON – The Senate on Monday was poised to end its deadlock and approve a historic overhaul of the nation’s financial regulatory system as two more Republicans said they expect to support the legislation.

Sens. Olympia Snowe, R-Maine, and Scott Brown, R-Mass., said Monday they would join Sen. Susan Collins, R-Maine, and nearly all Democrats in voting for the bill.

Majority Leader Harry Reid, D-Nev., said he expects a vote this week. As Democrats control 58 of the Senate’s 100 seats — and one Democrat has expressed serious concerns with the bill — supporters now believe they have the 60 votes needed to cut off extended debate and pass the measure.

“While not perfect,” Snowe said in a statement late Monday, “the legislation takes necessary steps to implement meaningful regulatory reforms, create strong consumer protections and restore confidence in the American financial system.”

Snowe’s decision was not a surprise; she has voted with Democrats on several key issues recently.

Brown’s decision came as he faced enormous political heat back home.

Activists held an event Monday near the Boston Marathon finish line in Copley Square before Brown’s midday announcement to urge him to vote yes. After he said he would, Lizzi Weyant, an attorney for MASSPIRG, a public interest group, called Monday “a proud day for the Bay State.”

However, members of 14 state “tea party” groups circulated petitions advising Brown to vote no and met his staffers Friday in Boston.

“Please recall that we supported you, campaigned for you and elected you to the Senate because you convinced us that you believed in fiscal responsibility,” the tea party petition says. “If you truly believe in those values, you cannot, in good conscience, support this outrageous attempt to nationalize the financial industry.”

In a statement, Brown said he appreciated efforts to improve the bill.

“As a result, it 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,” Brown said. “It includes safeguards to help prevent another financial meltdown, ensures that consumers are protected and it is paid for without new taxes.”

At stake is legislation that addresses many of the problems that led to the financial industry’s 2008 collapse. The House of Representatives passed the bill last month.

The measure — the product of painstaking negotiations, largely among Democrats — would set up a new consumer agency to write rules for credit products such as mortgages, student loans and credit cards. It would require financial institutions to spin off some riskier investments, and it gives the government tough new tools to deal with large, ailing institutions.

The path to the right math for the bill’s passage has been long and winding.

In May, Brown, Collins, Snowe and Charles Grassley, R-Iowa, sided with Democrats on a similar version of the legislation. Two Democrats, Wisconsin’s Russell Feingold and Washington’s Maria Cantwell, were opposed.

Cantwell has since said she will vote yes, because the new bill gives regulators tougher tools to use to crack down on the derivatives market. Feingold continues to have serious concerns.

Collins, pleased that the bill strengthened capital requirements for large institutions, said she was “inclined to support” the bill.

Grassley would not comment Monday.