Former President Ford endorsed the proposed new Panama Canal treaties yesterday. White House aides hope it will improve the chances of winning Republican support in the Senate for ratification.

After a 90-minute meeting with Carter administration officials at his vacation home in Vail, Colo., Ford described the treaties as "an important step forward" and said he is "absolutely convinced it's in the national interest of the United States that the two treaties be approved."

Ford was briefed on details of the treaties by Ambassador Sol Linowitz, one of the two chief American negotiators in the canal talks with Panama, and by Gen. George Brown, chairman of the Joint Chiefs of Staff. At the former President's request, the administration also arranged to fly Brent Scowcroit, Ford's national security adviser, to Vail for the meeting.

While Ford was being briefed, a similar session was being held in Washington to acquaint his former Secretary of State, Henry A. Kissinger, with the details of the treaties. Kissinger, who voiced qualified support for the agreements on Monday, was also expected to call for ratification.

The well-orchestrated wooing of Republican leaders was part of a concerted White House effort to line up bipartisan support for what they concede will be an uphill Senate battle.

The treaties, according to the White House, would turn over the canal to Panama in stages, with Panama assuming complete control by the year 2000, and would give the United States the right to defend the canal's neutrality indefinitely.

Ratification will require approval by two-thirds of the Senate, or 67 votes if all senators vote. This makes the 3 Republicans' votes crucial.

The GOP was deeply divided over the canal issue last year, with Ford defending the negotiations for a new treaty and his primary-elections opponent, Ronald Reagan, bitterly assailing him. The former President's endorsement yesterday poses the possibility of a replay of the issue, which cost Ford heavily in the primaries. Reagan has already announced his continued opposition to giving up U.S., control of the canal.

Late yesterday, Ford called President Carter at Camp David, Md., to inform him of the endorsement.Carter, according to the White House, thanked his predecessor "for this example of bipartisan support on a question so clearly important to our national interest and security."

It remained unclear yesterday whether the Carter administration would attempt to enlist Ford and Kissinger as active campaigners for ratification. One administration political operative said the White House would like to push Ford into an active role "as far as he is willing to go."

But that subject did not come up during the meeting in Vail, according to a well-placed source. After the session, the former President told reporters he would "do what I can" to help gain ratification.

"I hope my endorsement of the negotiations and the two treaties will be helpful and beneficial in securing congressional approval," he said. "It's going to be a tough battle."

While Ford was endorsing the treaties, opponents were making statements calling for their defeat. Louisiana Gov. Edwin Edwards urged state legislatures to pass resolutions opposing the treaties, and William J. Rogers, national commander of the American Legion, said that giving up sovereignty over the canal would be the equivalent of losing a major military battle.