Business lobbyists are concerned that an escalating Senate fight over judges may stymie legislation to keep hundreds of billions of dollars flowing for highway construction, an overhaul of American energy policy, and for the extension of the government’s underwriting of terrorism insurance.

One trade group, the Associated General Contractors of America, which represents the construction industry, is so worried about a Republican threat to limit Democrats’ ability to block President Bush’s judicial nominees – and the prospect the Democrats would retaliate by bringing the Senate to a halt – that it has urged Republican leaders to postpone a confrontation over the judgeships.

The federal highway construction program goes out of business May 31 unless Congress renews it. The Arlington, Va.-based contractors’ group has “informally” asked Senate Majority Leader Frist to postpone triggering what lawmakers call “the nuclear option” on judicial appointments before the Senate passes highway legislation, a lobbyist, Brian Deery, said. Dr. Frist, a Tennessee Republican, says he hopes to schedule a vote on the highway bill this week.

“Clearly we are very concerned about the impact on the transportation bill,” particularly if it becomes a test of the Democrats’ resolve to shut down the Senate, Mr. Deery said. “We are really concerned that outside forces like the nuclear option are going to keep it from moving forward.”

The nuclear option is Congress-speak for a proposed rules change that would eliminate filibusters on judicial nominations. Republicans control the Senate 55-45; it takes 60 votes to end a filibuster, a tactic that lets a minority block a final vote on legislation or a presidential nomination.

Business lobbyists are also pressing Congress to move quickly on bills setting energy policy and extending beyond this year a law enacted after September 11, 2001, that provides federal underwriting of private insurance for damage inflicted in terrorist attacks. Another priority is an extension of tax credits for businesses hiring welfare recipients.

The fight over judges has been brewing since the 1980s, when the Democratic-controlled Senate blocked President Reagan’s nomination of Robert Bork to the Supreme Court.

Republicans got even by preventing hearings or votes on more than 60 of President Clinton’s judicial nominations. Using the filibuster, Democrats have blocked floor votes on 10 of Mr. Bush’s nominees to appeals courts.

At the start of his second term, Mr. Bush resubmitted the names of seven of the 10 nominees. Mr. Frist’s proposed rules change would eliminate the filibuster only for judicial nominees, letting a simple majority of 51 votes decide their fate. Filibusters to block legislation would still be permitted.

Congress, unable to agree on the size of a six-year highway and transportation construction program, has extended temporary financing six times since 2003. Prospects for the long-term measure remain clouded by a possible veto by President Bush if Congress increases the $284 billion price tag and the possibility Democrats will shut down Senate business.

“It would be a political blunder for Bush if he continues to threaten that,” said Brad Larson, president and chief executive officer of Meadow Valley Corporation, a Phoenix-based construction company. “If the Democrats are the cause of 1 million jobs being lost, it’s a huge blunder on their part.”

Failure to extend federal highway funding could disrupt construction programs or the award of new contracts within a month or two, Mr. Larson said. “For those companies who have an abundant amount of federally funded work, this bill is critical,” he said. Among other business priorities is a proposal to create a $140 billion fund to compensate asbestos-exposure victims and end lawsuits that have bankrupted more than 70 companies. Senate leaders are trying to reach a bipartisan compromise on that measure.

“Anybody who is trying to get legislation will express the same concerns I have about the Senate coming to a screeching halt,” said Bruce Josten, executive vice president of the U.S. Chamber of Commerce at Washington.

The Chamber of Commerce is part of an energy-bill coalition that includes London-based BP Plc, Duke Energy Corporation based in Charlotte, N.C., and CSX Corporation, based in Jacksonville, Fla. The Chamber of Commerce is also part of a group pushing for changes in telecommunications law that includes Atlanta-based BellSouth Corporation and New York-based Verizon Communications.

At a White House meeting last week with lawmakers, Mr. Bush repeated his call for Congress to pass the first energy bill of his presidency. Montana Democratic Senator Baucus warned the president that he wouldn’t get his wish if Senate Republicans sought to change the rule on judicial filibusters, according to Mr. Baucus’s spokesman, Barrett Kaiser.

Mr. Baucus reminded the president that “it would be difficult to get anything passed, let alone an energy bill, if the Senate came to a halt,” Mr. Kaiser said in a telephone interview.

The House of Representatives last week approved and sent to the Senate legislation that opens a wildlife refuge in Alaska to oil exploration and protects makers of a gasoline additive from product liability lawsuits.

Mr. Frist, who has said he wants to reach an accommodation with Democrats over judicial nominees, has ducked questions about whether he has the necessary votes to impose the nuclear option.

Among Republican senators who have expressed reservations about eliminating the judicial filibuster are John McCain of Arizona, Susan Collins and Olympia Snowe of Maine, Lincoln Chafee of Rhode Island, Gordon Smith of Oregon, and John Warner of Virginia.

It would take at least 50 Republicans to change the rule, with Vice President Cheney breaking a potential 50-50 tie.

The Senate Judiciary Committee has forwarded the names of three of Mr. Bush’s seven disputed judicial nominees to the full Senate: William G. Myers III of Idaho, a mining company lobbyist; Priscilla Owen, a Texas Supreme Court justice, and Janice Rogers Brown, a California Supreme Court justice.

Dr. Frist has given Pennsylvania Senator Specter, the panel’s chairman, time to try to line up the 60 votes to break a filibuster against Mr. Myers, the first of the seven nominees to be cleared by the judiciary committee.

Mitch McConnell, the no. 2 Senate Republican leader, said last week “there’s no deal” with Democrats on averting a showdown on judicial nominations. “I think the other side has dug in,” he said. Democrats are sticking to “the principle that 41 members of the Senate can dictate to the president who ought to be” on the appeals courts and the Supreme Court, he said.

Senate Minority Leader Reid, a Nevada Democrat, urged Dr. Frist to schedule the highway bill as the Senate’s next order of business rather than vote on Mr. Bush’s disputed judicial nominees. “If he moves to proceed to the highway bill, he can allow us to do the work that the American people sent us here to do,” Mr. Reid said in a letter to Mr. McConnell last week.

Mr. Reid later told reporters that forcing a rules change on judicial filibusters would mean “the Senate’s not going to move along like it has.”