Democrats came out swinging Thursday against a Republican proposal to change consumer protection rules in the new Wall Street reform bill.

President Barack Obama and Democrats in Congress loudly criticized an amendment to be offered by Sen. Richard Shelby (R-Ala.) and other Republicans that, Democrats said, would weaken consumer protection.

"Today, the Senate is considering a Republican amendment that will gut consumer protections and is worse than the status quo," Obama said Thursday in a statement. "I will not allow amendments like this one written by Wall Street’s lobbyists to pass for reform."

Democrats in the Senate also took aim at the proposal ahead of a vote expected either today or tomorrow on the Shelby proposal.

"It's more like 'lapdog,' not 'watchdog,'" said Sen. Jack Reed (D-R.I.), a senior member of the Senate Banking Committee. "All bureaucracy, no bite."

Sen. Bob Menendez (D-N.J.) accused Republicans of "obfuscating" and trying to "deceive" on the amendment, by framing it as adequate consumer financial protection.

Consumer protection had been a key sticking point in the negotiations between Shelby and Sen. Chris Dodd (D-Conn.), the chairman of the Senate Banking Committee, who had opted for a more aggressive regulatory scheme than Republicans preferred.

Update, 1:56 p.m.: Republicans pointed to a number of groups' support for the Shelby amendment as evidence of Main Street support for the measure. Republicans touted endorsements from the U.S. Chamber of Commerce, National Federation of Independent Business (NFIB), Retail Industry Leaders Association (RILA), and other groups.