By WSJ Staff

How the U.S. economy will fare over the next few years will depend on the outcome of a likely power struggle between politics and finance, an outspoken economist said Monday.

The U.S. economy could face a similar financial crisis to the one it’s emerging from unless the government tackles the problem that some banks remain too big to fail, Simon Johnson, economist at the MIT, told a panel at the American Economic Association.

The U.S. Congress has proposed legislation to drastically overhaul financial sector regulation, including measures to seize control of troubled big banks and to cut the powers of the Federal Reserve, the U.S. central bank.

The crisis that ended in 2009 has only exacerbated the problem because of the resulting financial sector consolidation, Johnson said. There are now six big banks that could soon engage in the sort of excessive risk-taking that led to the recent crisis because of a belief that the government would bail them out if they’re in trouble.

“Goldman Sachs has become the world’s largest hedge fund underwritten by the U.S. government,” the MIT economist said. The other five banks he mentioned as posing system risks to the economy are Bank of America, Citibank, J.P. Morgan Chase, Morgan Stanley and Wells Fargo.

It will be harder to deal with any new crisis because the U.S. Federal Reserve has likely exhausted its ammunition to counter a financial meltdown after it cut rates close to zero and took other emergency lending steps, Johnson warned.

“A crisis strengthens the oligarchs who survive,” Johnson said.