The House Foreign Affairs Committee yesterday approved a declaration that the War Powers Resolution of 1973 applies to the Grenada invasion, setting up a potential clash between Congress and President Reagan if U.S. troops do not leave the small Caribbean island by Dec. 24.

The brief paragraph of legalese makes no comment on the wisdom or propriety of the invasion, and thus won the support of all the committee's Republicans. Discussing the Grenada invasion before the vote, Republicans offered praise and Democrats, for the most part, had only restrained criticism.

The committee voted 32 to 2 for the resolution, which says the war powers law, which bars a president from keeping U.S. troops in hostile situations overseas longer than 60 days without congressional approval, took effect the moment the invasion began Tuesday morning.

But Deputy Secretary of State Kenneth W. Dam told Congress that the administration will not concede the validity of the 60-day provision.

"The administration has serious doubts as to the automatic cutoff provision of the war powers legislation," Dam said in testimony before the Senate Foreign Relations Committee. However, he said he doubts the issue will come to a head: "It is conceivable, but it seems to me extraordinarily unlikely" that American soldiers will still be on Grenada in 60 days.

"When history is written on this," Rep. William S. Broomfield (R-Mich.), the committee's senior Republican, said of the invasion, "they will look back and say this was one of the United States' finest hours."

Two Democrats, Ted Weiss (D-N.Y.) and George W. Crockett Jr. (D-Mich.), voted against the committee resolution because it does not contain language condemning the military action.

Weiss argued that the invasion was illegal. After the committee session he suggested that Reagan could be impeached for unilaterally starting a war. The Constitution says that the power to declare war belongs only to Congress.

Rep. Peter H. Kostmayer (D-Pa.) also blasted Reagan for the military invasion of "a country small and weak. I believe this will come to be an action of which all Americans will be greatly ashamed."

For the most part, though, congressional Democrats continued to hedge their bets on Grenada. Many said they still lacked sufficient information to conclude whether or not the military venture was wise.

The Democrats seemed to have been impressed by the remarks of American medical students evacuated from Grenada by the U.S. soldiers. The students offered effusive thanks and praise for the rescue.

Citing these comments, Sen. Christopher J. Dodd (D-Conn.), a harsh critic of Reagan's military policies elsewhere in the region, said that "On the question of safety and security, I think the action is warranted." But Dodd said he did have doubts about the legality of the action under the constitution of the Organization of Eastern Caribbean States.

Yesterday's actions on the War Powers Resolution mean that, if U.S. soldiers are still on Grenada in December, there will almost certainly be a replay of the constitutional clash between Congress and the White House that took place over the Marine force in Lebanon.

Then, too, Congress insisted that the War Powers Resolution limited Reagan's authority to keep troops on station. Then, too, the president suggested that the legal limits are constitutionally invalid.

The Lebanon controversy was resolved, at least temporarily, when Reagan compromised with congressional leaders on legislation that invoked the war powers law but gave the president virtually a free hand in Lebanon for 18 months. In signing that compromise measure, Reagan protested that he still doubted the validity of the time limits in the War Powers Resolution.