The Reagan administration and Congress acted yesterday to warn Philippine President Ferdinand Marcos that unless the forthcoming presidential election in his country is visibly "free and fair," he risks losing all support at home and in the United States.

Appearing before a House Foreign Affairs subcommittee, Assistant Secretary of State Paul D. Wolfowitz predicted that a fraudulent election would result in "a complete collapse of confidence" in the Marcos government and a "disaster of large and indefinable proportions" for its relations with Washington.

"The United States itself has a great stake in assuring that the next Philippine presidential election, whenever it is held, is a free and fair one," Wolfowitz said. "We will do whatever we reasonably and appropriately can to achieve that end."

Marcos announced Nov. 3 that an election would be held Jan. 17. The opposition is seeking a postponement to March 17 to give it more time to organize and campaign.

Wolfowitz, the State Department's top Philippines expert, did not take a position on a specific date for the election but called it "essential" that Marcos reach an agreement with the opposition. If the opposition thinks Jan. 17 is too soon, Wolfowitz said, "then some delay would be in order."

Wolfowitz indicated that the administration would support a sense-of-Congress resolution, reported unanimously by the Asian and Pacific affairs subcommittee yesterday, which states in part that Congress intends to take into account "the degree to which democratic reforms are taking place" in the Philippines when it considers future economic and military aid.

The resolution calls for respect of the constitution by Marcos in fixing the date and modalities of the election, the appointment of an impartial commission on elections staffed by "politically independent commissioners," accreditation of a citizens' monitoring organization known as NAMFREL, and "adequate access" by the opposition to the local media.

The resolution -- worked out by Rep. Stephen J. Solarz (D-N.Y.), chairman of the House subcommittee, and Chairman Richard G. Lugar (R-Ind.) of the Senate Foreign Relations Committee -- is expected to be approved overwhelmingly by both chambers this week.

Also appearing before the House panel yesterday was Assistant Secretary of Defense Richard L. Armitage, who said that despite the spreading communist insurgency in the Philippines, the Pentagon believes that the United States will be able to maintain its two big bases there.

"I would like to state clearly and for the record that currently we are not planning to relocate our facilities in the Philippines," he said. "Indeed, we have every reason to expect that we will be there long after the current military bases agreement becomes indefinite . . . in 1991, and that arrangements for continued access can be arrived at with any noncommunist government."

Armitage indicated that this assumption explained Defense Department plans to proceed with upgrading the two bases. But he said recent news reports that the Pentagon planned to spend $1.3 billion on the bases, using figures that local U.S. commanders gave a Senate subcommittee, were erroneous.

He said the Air Force and the Navy are "reviewing programs" for fiscal years 1987 through 1991 totaling $720 million. However, he said this figure has not been approved by the Defense Department and is likely to be cut.

The Pentagon has requested $121 million for fiscal 1986. The House has appropriated $80 million and the Senate $114 million, Armitage said.