Elizabeth Warren and Elijah Cummings have not given up fighting the roll-back to the Dodd-Frank law signed by President Obama in December.

The two liberal Democrats are asking regulators for transparency about what banks are up to following the repeal of the rule on swaps transactions, having already been denied the information by the banks themselves.

The provision, known as the "swaps push-out," prevented banks from trading certain derivatives in their units that have deposit insurance backed by the federal government. It was repealed as part of a must-pass bill to avert a government shutdown in December, despite a Warren-led Democratic rebellion.

Warren, a Massachusetts senator, and Cummings, a Maryland representative, told regulators in a letter sent Thursday that the banks needed to provide more information about the transactions they have made following the repeal.

The banks "can either have access to taxpayer guarantees or they can keep big secrets, but they can't do both," the lawmakers wrote.

In the letter, Warren and Cummings said that they already requested information on swaps transactions from Citigroup, Bank of America, JPMorgan Chase and Goldman Sachs, but had not received a response.

"Without this understanding, the country risks moving blindly toward the same financial meltdown that plunged the economy into recession seven years ago," they said.

Although the swaps push-out wasn't supported by all regulators or Democrats when it was incorporated into the 2010 Dodd-Frank law, some of its former detractors, such as former House Financial Services Committee Chairman Barney Frank of Massachusetts, argued that allowing it to be repealed as part of unrelated must-pass legislation set a bad precedent for allowing Wall Street to chip away at Dodd-Frank's reforms.

Even though they lost that fight, Warren and Cummings are pushing for the regulators to disclose the size and scope of the banks' swaps contracts, and the extent to which the trades are being made by insured units of the banks.

They gave an Aug. 6 deadline to the agencies, which include the Federal Reserve, Federal Deposit Insurance Corporation, Office of the Comptroller of the Currency and Commodity Futures Trading Commission.