Senator Christopher J. Dodd, the Connecticut Democrat who heads the Senate Banking Committee, said the bill became a reality because of cooperation from Senator Richard C. Shelby of Alabama, the panel’s ranking Republican, and many other lawmakers on both sides.

President Obama has spoken derisively of the multi-page, fine-print statements familiar to millions of credit card-users. Last week, he told a receptive crowd in New Mexico that “you should not have to worry that when you sign up for a credit card, you’re signing away all your rights. You shouldn’t need a magnifying glass or a law degree to read the fine print that sometimes doesn’t even appear to be written in English.”

Senator John Kerry of Massachusetts, a senior Democrat on the finance and commerce committees, said, “We’ve got too many hard-working families in Massachusetts struggling to keep their heads above water, and the last thing they need is to get whacked with unfair credit card fees.”

Among other things, the Senate measure would prohibit companies from raising interest rates on existing balances unless a card holder was 60 days behind, and then it would require the rate to be restored to its previous level if payments were on time for six months. Consumers would have to be notified of rate increases 45 days in advance. And companies could not charge a late fee if they were late processing a payment.

Statements would have to be mailed 21 days before a payment was due. It would be harder for companies to issue cards to people under age 21. Rates could not be increased within the first year, and promotional rates would be in force for at least six months.

Credit card debt has increased by 25 percent in the last decade, with delinquency rates up by more than a third since 2006, according to statistics cited by the White House. Americans pay $15 billion in penalty fees a year, accounting for about 10 percent of the industry’s revenues. About a fifth of those carrying credit card debt pay more than 20 percent in interest.

One amendment attached to the Senate bill by Senator Tom Coburn, Republican of Oklahoma, would restore a Bush administration policy allowing loaded guns in national parks. That provision is not in the House version, so there may be discussions between the two chambers over the issue.