“The president reiterated his belief that we are open to ideas and eager to work with anyone who is willing to work with us regardless of party,” Mr. Gibbs said. “He also made clear that bipartisanship should not be equated with an openness to lobbyists, loopholes and special interest carve outs and that he would be unwilling to negotiate on some key issues, and that he could not accept bad policy in pursuit of bipartisanship.”

The legislation seeks to contain the risky practices that led to the financial collapse in 2008 and the worst recession since the Great Depression. It would give the Federal Reserve oversight of the largest and most interconnected financial institutions, those with at least $50 billion in assets.

And it would let the Treasury secretary — with support from regulators and the approval of a panel of three bankruptcy judges — take over any company that posed systemic risk to financial stability, and essentially force the company out of business.

At a lengthy briefing at the White House, the Treasury secretary, Timothy F. Geithner, said he was confident a bill would be approved. “This is going to be the most sweeping set of reforms we have contemplated, as a country, since those put in place after the Great Depression,” he said. “We do not want to have the American taxpayer ever be in the position again where they’re forced to choose between putting billions of dollars of taxpayers’ money at risk or facing catastrophic collapse of the financial system.”

Facing reporters outside the White House, Mr. McConnell repeated his assertion that the Senate bill would encourage bailouts by creating a $50 billion fund essentially to dismantle companies that are so big their failure would endanger the economy.

He demanded further negotiations. “My message to the president, quite simply, was, ‘Let’s get back to the table,’ ” he said.

But Mr. McConnell also struggled to answer accusations that Republicans were doing the bidding of big banks. Pressed by reporters to explain why major Wall Street companies were so strongly opposed to the legislation if it would guarantee future bailouts for them, Mr. McConnell did not answer directly but said that community banks in his home state of Kentucky also opposed the bill.