Senate Republicans vow to oppose a Democratic effort to begin debate next week on a proposed crackdown on Wall Street unless a bipartisan accord is reached, senior Republican aides said on Friday.

While some Republicans are expected to eventually back President Barack Obama's bid for financial regulatory reform, the two sides are skirmishing over Monday's vote on cloture, which would start debate on financial reform.

Democrats need at least one of the 41 Republican senators to vote with them on Monday, but Republicans were standing firm, senior aides said. We feel confident that all our senators will oppose cloture in order to continue bipartisan negotiations, one aide said.

Republican leadership has commitments from all Republican senators to vote no unless there is an agreement on the legislation, another aide added.

President Barack Obama scolded Wall Street on Thursday for its furious efforts to fight tighter regulation, saying the United States was doomed to another financial crisis if reforms were not implemented

If Democrats fail to win the vote, the legislation would not be killed but would be delayed. To prevail in Monday's vote, the Democrats need support from 60 senators in the 100-member chamber.

Republican aides say Senate Democratic Leader Harry Reid prematurely forced the vote, set for 5 p.m. EDT (2100 GMT), to make Republicans either accept it or look like they are blocking curbs on Wall Street, which may upset many voters ahead of November mid-term congressional elections.

Reid's doing this vote for one reason: He wants headlines reading, 'Republicans filibuster (block) financial regulation,' a senior Republican leadership aide said.

Once Reid gets the headline, I think (Senate) negotiators will reach an agreement that Reid approves, the aide said. They are close to an agreement now.

The financial reform bill authored by Democratic Senator Christopher Dodd would bring new oversight to hedge funds and derivatives while cracking down on risky bank trading and putting in place protections for financial product consumers.

It would also establish a system for unwinding troubled financial companies to prevent a repeat of catastrophes such as the collapse of Lehman Brothers in 2008.

The Lehman Brothers collapse came at the start of the deepest recession since the Great Depression, triggered by the implosion of the U.S. sub-prime mortgage derivatives market.

A chief target as a possible defector is Republican Senator Susan Collins, seen as one of the chamber's most moderate Republicans.

But Collins, to the delight of fellow Republicans, was quoted on Friday in The Washington Post as saying, I hope that Senator Reid abandons his plan to force a premature cloture vote on Monday. ... A divisive vote on cloture at this point would be unfortunate.

Jim Manley, Reid's press secretary, rejected Republican complaints. All Senator Reid is asking is to begin debate while these bipartisan negotiations continue, Manley said.

Stalling is not an option. We've been negotiating for months. ... We want a full and open debate with amendments offered by both sides, Manley said.

The broad legislative push by Obama and the Democrats comes as fraud charges against Goldman Sachs have thrown Wall Street and Republicans onto the defensive after months of working to weaken Democratic reform proposals.

(Editing by Todd Eastham)

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