As President Bush set off across the country to promote his social security reform plan to Americans, there were more signs that he will face stiff opposition in Congress. 

With the president on a road campaign to persuade Americans of the wisdom of his social security proposals, congressional Democrats have already fired a new warning shot.

In a letter, 44 Senate Democrats warn the president that the steps he has so far outlined to save social security will sharply increase the national debt, placing heavy burdens on future generations.

The Senate Democrats used the backdrop of a memorial to President Franklin Delano Roosevelt near the national mall to release the letter.

The U.S. retirement/pension system known as Social Security was part of President Roosevelt's New Deal, a package of economic stimulus measures to help the country recover from the Great Depression of 1929.

In recent congressional testimony and other comments, James Roosevelt Jr., President Roosevelt's grandson, said his grandfather would have opposed the proposals now being promoted by President Bush.

President Bush will not have an easy time getting his reform plans approved by Congress. 

While Republicans were generally enthusiastic about his State of the Union speech, which focused sharply on Social Security, many are nervous that failure on such an important domestic issue could cause Mr. Bush more trouble in his second term.

Moderate Republicans in the Senate are on record expressing deep concern about the details of the plan, and a key House Republican Thursday expressed similar feelings.

Congressman James McCrery, who chairs the House of Representatives subcommittee on social security, says the President risks giving Democrats a potent political tool.

The comments contrasted with more cautious remarks by Congressman McCrery moments after President Bush's State of the Union address, in which he also stressed Republicans should not think they can force a social security plan through without Democratic support.

"It is going to have to be done on a bipartisan basis, we're going to have to involve Democrats, we are going to have to listen to Democrats, because they I hope will come forward like the President did tonight with some specific suggestions as to how to solve the social security problem," said Mr McCrery.

President Bush, beginning a two-day cross-country trip to promote his reform agenda, repeated his pledge to consider all proposals from members of Congress, but also warned lawmakers, in his words, "not to play politics with the social security issue."

But with the entire Democratic caucus in the Senate coming out so forcefully against him, he has hard work ahead trying to persuade some moderate Senate Democrats to join him, while maintaining unity in Republican ranks on social security.