WASHINGTON - President Bush called on Congress yesterday to act immediately when it convenes next month to reinstate unemployment benefits for 750,000 people whose assistance will run out three days after Christmas.

Bush said the benefits should be paid retroactively to Dec. 28 once they are restored. He otherwise offered few specifics of the legislation he wants passed by Congress, where his party will be in control of the Senate and the House starting next month.

Unemployed workers "need our assistance in these difficult times, and we cannot let them down," Bush said in his weekly radio address.

"I have shared these concerns with the leaders of the House and the Senate, and they understand the need for early action," he said. "When our legislators return to the Capitol, I ask them to make the extension of unemployment benefits a first order of business. And the benefits they approve should be retroactive so that people who lose their benefits this month will be paid in full."

States typically provide laid-off workers with 26 weeks of unemployment benefits, and the federal government has routinely extended the benefits in particularly hard economic times. This year, Congress authorized a 13-week extension, but that authorization runs out Dec. 28.

Bush pointed out that the House and the Senate had passed differing versions of legislation that would have extended the benefits again, but had not reached a compromise before adjourning last month.

He did not mention that Democrats accused him last month of not pressing Republican leaders enough to reach a deal, or that they increased pressure on him in the past week to act immediately.

On Friday, Democrats on the House Ways and Means Committee said they would introduce a bill on the first day Congress was back in session that would provide an additional 26 weeks of coverage to laid-off workers. They said their approach would help not just the people whose benefits will end on Dec. 28, but also those whose benefits will expire after that at a rate of 90,000 a week and the 1 million people whose benefits have already run out.

"President Bush has said he is a compassionate conservative, but apparently that compassion does not extend to the unemployed," said Rep. Charles B. Rangel of New York, senior Democrat on the Ways and Means Committee. "He stood silent on the sidelines as Republicans in the House blocked an extension of unemployment benefits to millions of laid-off workers. We will introduce legislation to correct this inequity, and we hope he supports it this time."

The unemployment rate last month stood at 6 percent, equaling its highest rate since mid-1994. The figure represents 8.5 million people who do not have jobs but are looking for work. With the other major indicator of prosperity, the stock market, also in the doldrums, the White House has become increasingly concerned about the political implications for Bush as he heads toward his re-election race in 2004.

Polls show that voters give Bush much lower ratings on his handling of the economy than on his overall performance, providing Democrats one of the few political openings they have against a popular president.