The United States is facing a delicate balancing act as it sorts through the details of a sweeping overhaul of financial regulation.
Cracking down too hard could put Wall Street at a competitive disadvantage and stifle the nascent recovery on Main Street.
And yet doing too little, or the wrong thing, could lead to another more virulent crisis.
"What happens over the next two to three weeks will have drastic ramifications for the availability of credit, for the competitiveness of U.S. financial institutions, and for the U.S. economy," said Andrew Busch, a currency and public policy strategist at BMO Capital Markets in Chicago.
"The potential for negative unintended consequences … is extremely high."
Republicans backed down this week, allowing debate to begin on a nearly 1,400-page bill. But they haven't dropped their opposition to key parts of the legislation, including tough restrictions on derivatives trading and a proposed agency to regulate consumer financial products, such as credit cards and mortgages.
"We've got a long way to go," Alabama Senator Richard Shelby, the Republicans' chief negotiator, told Fox News Wednesday. "This bill is so far reaching, so complex, so vast in scope. It's going to take some debate."
Treasury Secretary Timothy Geithner accused the bill's opponents of scaremongering.
"Over the past year, opponents of reform have tried to convince the American people that these reforms will help Wall Street and hurt Main Street," Mr. Geithner told a Senate subcommittee. "These arguments won't work because they aren't true."
The two sides agree on roughly 90 per cent of what's in the bill. But Mr. Shelby identified two potentially far-reaching rules - on derivatives and consumer regulation - as the two main outstanding issues.
Already, roughly 100 amendments to the bill are making the rounds.
By far the greatest challenge will be agreeing on how to regulate the multi-trillion-dollar market for derivatives - financial contracts based on the price of an underlying asset. Critics have blamed an explosion of derivatives this decade for exacerbating the 2008 credit crisis by exposing the financial system to large and often unseen risks.
Section 716 of current bill would force major banks to spin off their lucrative swaps operations or lose the government backstop, including deposit insurance and access to the Federal Reserve's discount window. That could made banks such as Goldman Sachs and JPMorgan Chase a lot less profitable.
Former Federal Reserve chief Paul Volcker, now an Obama administration advisor, has proposed a milder rule that would allow banks to remain in the derivatives business. But it would bar them from trading those products on their own accounts - the sort of activity at the heart of the Securities and Exchange Commission civil fraud charges against Goldman Sachs.
As it now stands, the law would also require that virtually all derivatives be traded and cleared on regulated exchanges. Many custom-made derivatives are now traded in secret, directly between the parties involved.
Republicans say they have no objection to more transparency. But they warn the rule could shift business away from Wall Street and deprive some companies of appropriate and necessary hedging tools against swings in interest rates, currencies or commodity prices.
Arkansas Senator Blanche Lincoln, who drafted the derivatives rules, said she's open to changes. She has suggested, for example, that bank holding companies might be allowed to conduct swaps operations as long as it didn't affect the rest of the bank.
Beyond derivatives, the other major flashpoint is the creation of the Bureau of Consumer Financial Protection. The agency would be housed and funded by the Fed, but otherwise would operate independently.
The U.S. Chamber of Commerce has mounted a major lobbying and ad blitz to kill the agency. The Group warns that the consumer regulator would create a costly new bureaucracy and impose new burdens on businesses that offer some financial services, such as auto dealers and doctors. Democrats say the concerns are unfounded.
Still, the powerful Chamber is running television ads in key that feed into the fear of government intrusion among businesses.
"Ask yourself, do we really need an economic J. Edgar Hoover regulating orthodontists?" Chamber official Tom Quaadman said.
The Democrats hold a 59-41 edge in the Senate. They need at least 60 votes to overcome blocking tactics by Republicans and get the bill passed.
Any bill that passes the Senate must then be merged with a version that cleared the House of Representatives in December. That could take another month.