BATH — Automatic federal budget cuts that are scheduled to take effect March 1 would affect defense spending disproportionately, U.S. Sens. Susan Collins and Angus King said Thursday after touring Bath Iron Works, a major Maine employer that relies on defense contracts.

The tour was closed to the media, but Collins and King spoke afterward about the looming cuts, which could hamper future BIW contracts.

“We are still not building the number of ships that the Navy says that it needs to meet its military requirement,” said Collins, who serves on the Senate Appropriations subcommittee for armed services. “The worst thing we could do for our national security is to drop that number still further.”

King said, “The most significant threat to the national security of the United States today is the budgetary chaos in Washington, and I think that’s shameful. It’s something that’s entirely within our control.”

If Congress fails to act by March 1, widespread cuts will go into effect. Congressional Republicans and the White House remain at an impasse about whether any solution should include new revenue — probably through increasing taxes on the wealthy and closing corporate tax loopholes — or solely through budget cuts, as many Republicans insist.

With no compromise in sight, members of Congress appear to be trying to protect projects that are important to their own constituencies.

On Wednesday, King and Collins sent a letter to President Barack Obama, urging him to convene a meeting with congressional leaders to come up with a way to avoid the budget cuts, enact a new defense budget and address the federal deficit. The letter focused almost exclusively on defense-related jobs and mentioned the potential effects on BIW and the Portsmouth Naval Shipyard in Kittery.

“These jobs are not just a count of government billets, a macroeconomic statistic, or an unemployment rate fluctuation,” Maine’s senators wrote in the letter addressed solely to Obama. “These jobs provide financial security for our constituents and health insurance for their families.”

In the House, Rep. Chellie Pingree, D-1st District, has been urging her colleagues on the House Appropriations Committee to pass a stopgap measure that would continue funding the government at the same level but give the Defense Department authority to spend additional money.

That presumably would allow the Navy to move forward with awarding the next round of contracts for new destroyers, potentially to be built at BIW.

Pingree, who serves on the Appropriations Committee, and Rep. Mike Michaud, D-2nd District, also wrote to congressional leaders this week, urging them to take action.

BIW President Jeffrey Geiger said Thursday that any cuts to defense spending absolutely would affect the shipyard. He said the uncertainty is hard on the more than 5,000 employees.

“We’re a little more insulated in the near term because we have projects that already have been funded,” he said, referring to the five Navy ships that are under contract. But BIW, a division of General Dynamics, also needs future contracts.

King said an aircraft carrier based in Newport News, Va., that is supposed to deploy to the Persian Gulf is idle because of the threat of spending cuts. “They don’t have the money to pay for fuel,” he said.

Collins and King went on to tour Portsmouth Naval Shipyard on Thursday afternoon. That military facility also would be affected by cuts. A Pentagon report issued Wednesday said Maine civilian personnel would lose a total of $41 million in salary from the cuts.

Collins said perhaps even more important than halting the immediate cuts is passing a full-year defense spending bill. She said that bill has passed in the Republican-led House but has not been taken up in the Senate, where Democrats have the majority.

“Part of the problem in Washington is the blame game,” Collins said. “There is plenty of blame to go around, but I don’t think it’s productive. I’ve seen Congress go from impasse to crisis to short-term fix and then repeat the cycle all over again. That is no way to run a government.”

Collins said she is tempted to introduce the defense budget as an amendment to the next bill that comes before the Senate, just to prove a point.

“That’s a good idea,” King said. “You heard it here first.”

Washington Bureau Chief Kevin Miller contributed to this report.