WASHINGTON, Sept. 5 — Democrats in Congress are planning to introduce bills in the coming days that would prohibit a range of practices used to market subprime loans to people with weak credit histories or low incomes.

Senator Christopher J. Dodd of Connecticut, the chairman of the Senate Banking Committee and a candidate for the Democratic presidential nomination, said on Wednesday that he would introduce a bill that would prohibit mortgage brokers from steering people into subprime loans if they qualify for cheaper conventional mortgages.

The bill would also ban hidden brokerage fees that are rolled into higher interest rates and prepayment penalties that make it difficult for people to refinance.

Similar prohibitions are in a draft bill being circulated in the House by Representative Barney Frank, chairman of the Financial Services Committee. Mr. Frank is studying ways to hold investment funds that buy subprime loans liable for any practices that violate new rules against “predatory lending.”

“We’re in agreement on all those things,” Mr. Frank said on Wednesday, adding that he hoped to have his committee approve a bill before the end of October.

But mortgage lenders, a powerful lobbying force in Washington with considerable support from Republicans, are certain to fight the Democratic proposals.

Mortgage industry executives contend that some disputed practices, like prepayment penalties, offer crucial assurances to investors and help widen the pool of money available to low-income borrowers.

“I would urge against Congress making ham-handed interventions in the markets,” said Representative Richard H. Baker, Republican of Louisiana, at a hearing of the House Financial Services Committee.

The draft bills highlight the increased urgency among Democrats about responding to the recent meltdown in mortgage markets, particularly for subprime loans, and to a rising wave of home foreclosures as low initial teaser rates on about two million subprime loans must be reset by the end of 2008.

Mr. Dodd’s comments were an attempt to take control of an issue that some other Democrats, including Senator Charles E. Schumer of New York, had been discussing for some time.

As recently as two weeks ago, Mr. Dodd told reporters that he saw little need for legislation because many problems confronting homeowners could be addressed by federal and state banking regulators.

But on Wednesday, Mr. Dodd said, “Predatory lending needs to be stopped, which is why I intend to introduce legislation that will put an end to practices that have forced thousands of Americans into foreclosure.”

The Dodd and Frank bills are aimed primarily at subprime mortgages, which are made to people with poor credit ratings or low incomes and which carry higher interest rates than more traditional loans.

Subprime lending has grown at an explosive pace for the last decade, with about $1.2 trillion outstanding. The practice has helped increase the share of families that own their homes to a record 69 percent, from about 65 percent a few years ago. Much of that increase has been among minorities.

But the delinquency rate on subprime loans has soared to about 13 percent, and most analysts predict that it will climb much higher. Mortgage lenders sharply lowered their underwriting standards in 2005 and 2006, using low introductory interest rates to lure hundreds of thousands of people into borrowing more than they could afford.

Mark Zandi, chief economist at Moody’s Economy.com, predicted that 20 percent of all subprime mortgages made in 2006 will be in foreclosure by 2011.

The Democratic proposals would attack several practices that advocacy groups for low-income homeowners have singled out. The first is prepayment penalties, which are rare for borrowers with good credit but common among subprime borrowers. The penalties make it very expensive for a person to refinance a subprime mortgage in less than two years, and sometimes in less than three years.

Defenders of prepayment penalties say they reduce the risks for investors who buy mortgages and thus help provide capital for low-income home buyers. Defenders also note that such penalties allow a lender to offer the low initial teaser rates, which were highly popular with many borrowers.

The Democratic measures would also restrict if not prohibit so-called yield spread premiums, which are sales commissions to mortgage brokers that are largely invisible to home buyers because they are paid through a higher loan rate rather than through an upfront payment. Critics argue that yield spread premiums are deceptive, but defenders say they benefit many borrowers who have little cash to pay the upfront closing costs on a loan.

The Democratic bills would also prohibit mortgage brokers from “steering” customers into taking a subprime loan even if they qualify for conventional mortgages. Some analysts have estimated that 20 percent to 40 percent of people who now have subprime loans could qualify for cheaper fixed rates.