Senate Republicans say they're prepared to work constructively with Democrats on a consensus financial reform bill. But this weekend, after the White House offered up a key substantive concession, they swatted President Obama's hand away in a fashion that was all too reminiscent of their strategy of opposition to health care reform.

"We ought to go back to the drawing board," Senate Minority Leader Mitch McConnell said on CNN Sunday morning.

Likewise, moderate Republican Scott Brown (R-MA), once considered a swing vote on regulatory reform, explicitly threatened to vote to block the bill from even being debated. Asked by CBS' Bob Schieffer if he'd filibuster the bill rather than let it come to the Senate floor, Brown was unequivocal: "In this particular instance, yes," he said.

The statements from Brown and McConnell came two days after the administration signaled it would push Democrats to drop a provision in their bill that Republicans broadly oppose: a $50 billion liquidation fund, raised by imposing a tax on major financial institutions, that would be used to cover the government's costs in the event that it has to liquidate an insolvent firm.

On Friday, after news of the administration's position broke, McConnell made clear he wanted to see more. "I appreciate the Obama administration's recognition of the need to substantively improve this bill," reads McConnell's official statement. "And I hope we can work with them to close the remaining bailout loopholes that put American taxpayers on the hook for financial institutions that become 'too big to fail.'"

Sen. Susan Collins (R-ME) also said she'd vote to block debate on the Democrats' bill, unless Republicans get to take a crack at it, but that was before the concession on the liquidation fund was first reported.

That leaves the two parties on the exact same collision course they embarked upon last week. Senate Majority Leader Harry Reid says he will try to bring the bill to the floor by week's end, daring Republicans to use Senate filibuster rules to block any debate on the bill at all. Recent events may strengthen the Democrats' hand. On Friday, the Securities and Exchange Commission charged Goldman Sachs with securities fraud--a case they rightfully argue highlights the need for expedient passage of legislation imposing tougher rules on Wall Street. And Republican leaders have been hard pressed to explain away their attempts to secure donations from Wall Street in exchange for their efforts to weaken the bill.

If Republicans follow through on their threat to block the bill from coming to the floor, it will take the political fight over regulatory reform in a new direction.