Washington ? The most sweeping new controls on financial institutions since the Great Depression are a big step closer to approval in Congress.

The changes, aimed at preventing a recurrence of the crisis that knocked the nation’s financial system to its knees in 2008, advanced Wednesday when Republicans abandoned their blockade in the Senate. Now, the battle begins over crucial details and that could take at least two weeks. The House already passed its version.

Democrats and Republicans agree the Senate will ultimately pass landmark changes. Democrats said the Republicans had given in after three days of votes to block debate, realizing they were on the losing end of a battle for public opinion. GOP lawmakers said they would now switch to trying to change the bill on the Senate floor.

‘Immense pressure’

Sen. Sheldon Whitehouse, D-R.I., said, “There’s been immense pressure bottled up inside the Republican caucus through these last three votes. A lot of their members have been very deeply unhappy with the direction their leadership has been taking them. Better heads prevailed.”

The Republican retreat came one day after senior executives of Wall Street giant Goldman Sachs were denounced by lawmakers from both parties at a marathon Senate hearing.

President Barack Obama, winding up a Midwest tour promoting the legislation, told reporters he was pleased the debate would proceed and that he hoped to sign a final version “very soon.”

“We’ll end up having a safer, more secure financial system,” Obama said, “and I think banks and other financial institutions can get back to making money the old-fashioned way by lending it to companies to build business and create jobs and do all the things we want our financial system to do.”

Both Democrats and Republicans will attempt to change the underlying bill. Republicans will take particular aim at the magnitude of consumer-protection provisions that Obama says are vital. Liberal Democrats are expected to seek to limit the size of banks.

The GOP decision to relent came after Sen. Richard Shelby, the top Republican on the Senate Banking committee, told his colleagues that he could win no further concessions from Banking Committee Chairman Chris Dodd in private talks. He said Dodd did agree to adjust some provisions that Republicans had complained would permit further bank bailouts.

‘A real debate’

But there were already signs that some Republicans were growing weary of continuing to block the bill after Obama and other Democrats accused them of siding with Wall Street, an institution that rivals Congress in its unpopularity.

“The point of all of this was to make sure that as long as those discussions could bear results that we would support that effort,” Republican Sen. Olympia Snowe of Maine said of her party’s objections.

“It is not just Republicans who are going to offer amendments,” said Sen. Bob Corker, a Tennessee Republican who negotiated with Dodd on portions of the bill.

“This may be a real debate, which would shock America.”

How the debate unfolds will determine whether the legislation achieves significant bipartisan support. Democrats still need 60 votes to get past procedural obstacles, a number they can’t reach without at least one Republican on their side.

The bill would establish a nine-member Financial Services Oversight Council, including the treasury secretary, Federal Reserve chairman and the heads of regulatory agencies to monitor markets for threats, such as the bubble in housing prices and mortgage-backed securities that preceded the financial near-collapse two years ago.

The Federal Reserve would begin policing large bank holding companies and interconnected nonbank institutions whose collapse might pose a threat to the economy. With approval of the council, the Fed could break up complex companies that posed a grave threat.

Most investment derivatives — such as the hundreds of billions of dollars in complex instruments blamed for accelerating the crisis two years ago — would have to be traded on regulated exchanges.

Shelby said Wednesday he had received assurances that Democrats would adjust the bill to address GOP concerns that it would perpetuate bailouts of banks.