MILWAUKEE, May 19 - President Bush pressed Congress on Thursday to move ahead on overhauling Social Security.
But Republicans said the White House and Congressional leaders were concerned that the fight over judicial nominees was further endangering any bipartisan deal on the retirement system and other high-profile issues.
Mr. Bush traveled here to make a pitch to younger workers that his plan to establish investment accounts and cut benefits from promised levels for many future retirees was the best way to assure that the government retirement program would provide them financial security in their old age.
His initiative, the centerpiece of his domestic agenda until now, is increasingly being overshadowed by a subject he never mentioned in his speech here, the fight on Capitol Hill over whether to end the use of filibusters to block nominees for federal judgeships.
Congressional aides and people who have discussed the issue with administration officials said top Republicans recognized that partisan rancor and Democratic threats to slow the Senate's business to a crawl could make the already tense climate less conducive to a deal on Social Security.
Still, those people said, Mr. Bush is committed to a fight over judicial nominees, on principle and because he is intent on making sure that Democrats cannot use the filibuster to block a Supreme Court nomination. Despite the obvious risks to his agenda, they said, the president and his aides believe that public opinion will not allow Democrats to block legislation on issues of concern to voters, including Social Security and high energy prices.
"The president feels that the nominees that he has selected for the federal bench deserve an up-or-down vote," Trent Duffy, a spokesman for Mr. Bush, told reporters aboard Air Force One en route to Milwaukee. "But he also strongly believes that Congress can do other things in the meantime, that the Senate needs to pass an energy bill, that we have activity on Social Security and that the rest of this country's agenda and the business of the country needs to move forward."
For a few hours, Mr. Bush tried to turn the spotlight to his case that younger people would benefit from the chance to invest part of their Social Security taxes with Wall Street and that reducing the benefits of middle-income and well-off retirees in the future would be a fair way to assure the solvency of the retirement system.
The real political pain, he suggested, would be felt by any members of Congress who failed to make the tough choices needed to get something done.
"There's a lot of young Americans who are beginning to pay attention to this issue and say, 'Wait a minute, I'm not contributing hard-earned money into a system that's going broke, and I don't like what I hear,' " Mr. Bush said to an invited audience at the Milwaukee Museum of Art. "And I expect members of both political parties to set aside their parties and focus on the good of the United States of America."
Republicans said there were already signs that the filibuster fight was complicating the agenda. The White House had made clear, for example, that it wanted a quick floor vote on John R. Bolton's embattled nomination to be ambassador to the United Nations, but it will now have to wait until the debate over the judicial nominees plays out, giving Democrats more time to rally opposition to Mr. Bolton.
"It's a risk for both sides," said a top aide to a senior Republican senator who insisted on anonymity to assess the stakes more candidly. "It's the Republican responsibility to govern. But to the extent Democrats have a responsibility not to block solutions, they're at risk, too."
Some people who support Mr. Bush said the divide over Social Security was so deep that the filibuster fight would not drastically alter the dim outlook for measures to win bipartisan support and be signed into law this year. The supporters said the controversy made the long odds even longer.
"Certainly it's going to make it more difficult in the Senate to get anything done," said Michael Tanner, director of health and welfare studies at the Cato Institute, the libertarian research group that has long championed Mr. Bush's plan to add investment accounts to Social Security. "The bad blood there didn't need to get any worse."
If there is a bright lining, Mr. Tanner said, it is that much of the focus on Social Security has shifted from the Senate to the House, where the chairman of the Ways and Means Committee, Representative Bill Thomas, Republican of California, is trying to develop bills that might attract bipartisan support.
If Mr. Thomas should succeed, Mr. Tanner said, that could re-energize efforts to get something done in the Senate.