Representative Louie Gohmert, Republican of Texas, said the president’s proposal would, in effect, establish the unemployed as a new “protected class.”

Mr. Gohmert said the proposal, if passed, would encourage litigation by sending a message to millions of Americans: “If you’re unemployed and you go to apply for a job, and you’re not hired for that job, see a lawyer. You may be able to file a claim because you got discriminated against because you were unemployed.”

“This will help trial lawyers who are not having enough work,” Mr. Gohmert said.

The Labor Department reports that 14 million people are unemployed. About 43 percent of them — six million people — are classified as long-term unemployed, having been out of work for 27 weeks or more. Of that group, nearly 4.5 million have been unemployed for a year or more. The average duration of unemployment is 40 weeks, the longest in more than 60 years.

Charges of employment discrimination tend to increase in a sluggish economy with a high jobless rate. In the 2010 fiscal year, which ended last Sept. 30, job bias charges filed with the employment commission reached a record of nearly 100,000, up 20 percent from 2007.

In many cases, lawyers said, it may be difficult for job applicants to show that they were turned down because they were unemployed. On the other hand, lawyers said, some employers and recruiters have posted job openings on the Web with the message that “no unemployed candidates will be considered.”

Mr. Obama’s proposal is modeled, in part, on bills introduced by two Connecticut Democrats, Senator Richard Blumenthal and Representative Rosa DeLauro. The top Democrat on the House labor committee, Representative George Miller of California, supports the legislation.

“In a tough job market, where workers are competing against tens and sometimes hundreds of people for every available job opening, it is unjust for employers to discriminate against those who are unemployed,” Ms. DeLauro said.