A top U.S. Senate Democrat moved Monday to impose an immediate freeze on credit card interest rates, as congressional Democrats continue their ongoing efforts to rein in perceived industry abuses.

Sen. Christopher Dodd (D., Conn.), who chairs the Senate Banking Committee, introduced a measure that would freeze rates on existing balances until February, when tough new rules for the industry are slated to go into effect. Too many companies are using the delayed implementation of the new standards, which were passed by Congress in May, to push through aggressive rate and fee increases, Dodd said.

"No sooner had it been signed into law but credit card companies were looking for ways to get around the protections," Dodd said in a statement.

The measure is part of a populist push by Dodd, a fifth-term senator expected to face a tough re-election battle with Republican Rob Simmons, a former U.S. congressman, next year. His ties to the financial services industry and a loan program at the former Countrywide Financial Corp. have hurt his standing with voters, despite being cleared of violating Senate ethics rules in the mortgage loan issue.

Dodd has responded by even more aggressively embracing consumer issues that he has previously advocated for in the past. He joined with four other Senate Democrats last week to introduce a bill cracking down on checking-account overdraft fees and has said a new consumer financial protection agency will be a centerpiece of his committee's efforts to overhaul regulation of the financial services industry.

Those efforts, along with his being a key voice on health care issues, appears to be helping with voters. A Sept. 17 Quinnipiac University poll showed Dodd's disapproval rate among Connecticut voters was at 49%, his best score in six months, and that he'd narrowed the gap with Simmons to 5 percentage points in a potential head-to-head race in 2010.

Dodd's latest legislation is part of a broader effort by congressional Democrats to crack down on what they see as gaming of the new rules by card issuers. Reps. Barney Frank (D., Mass.) and Carolyn Maloney (D., N.Y.) have authored legislation in the House of Representatives that would move up the effective date of the new restrictions from February to December.

Frank, who chairs the House panel that approved the accelerated-date bill last week, has said he was disappointed that card firms had pushed through rate increases ahead of the new rules after asking lawmakers for extra time to comply with the new standards.

Maloney, in a statement released last week, said that "the card companies brought this on themselves."

Republicans have opposed the industry crackdown, but with only limited effect. The House measure would be limited to credit card firms with more than 2 million cards in circulation and would exempt gift cards.

-By Michael R. Crittenden, Dow Jones Newswires; 202-862-9273; michael.crittenden@dowjones.com