President Reagan gave his blessing yesterday to a compromise plan that would base the homeless MX intercontinental ballistic missile in old Minuteman silos and authorize development of a small, mobile, single-warhead missile for deployment in the next decade.

The new plan, the brainchild of the president's bipartisan Commission on Strategic Forces, quickly won modest endorsements from both Majority Leader James C. Wright Jr. (D-Tex.) and Minority Leader Robert H. Michel (R-Ill.), who were among congressional leaders Reagan met before he gave his statement of support. Wright said the plan was "less than ideal but probably the best we can get," and predicted that it would pass.

In a low-key statement in the East Room of the White House the president said that approval of the report, which calls for deploying 100 MX missiles in Wyoming and Nebraska, is "absolutely essential both for maintaining an effective deterrent and for achieving successful arms reductions."

His moderate tone reflected the administration's need for Democratic support to win deployment of the MX after two defeats in Congress. Reagan emphasized the bipartisan composition of the panel he appointed to rescue the MX, and singled out for special praise commission Chairman Brent Scowcroft, national security affairs adviser under President Ford, and Harold Brown, defense secretary under President Carter.

He also portrayed the MX as necessary to effective negotiation with the Soviets, and made no reference to critics' accusations that the 10-warhead missile, which Reagan called "the Peacekeeper," would increase the dangers of nuclear war.

One argument against basing the missiles in the supposedly vulnerable Minuteman silos is that they are tempting targets that could prompt the Soviets to launch a first-strike attack. Some contend that MX deployment in vulnerable silos also could encourage U.S. war planners to launch a first strike against the Soviets because a Minuteman-based MX would be unlikely to survive if the Soviets were to strike first.

The commission dismissed this argument last week, and with it much of Reagan's contention of a U.S. "window of vulnerability," by saying that the Soviets could not simultaneously destroy all elements of the U.S. strategic defense system, which includes submarines and bombers armed with nuclear missiles as well as land-based weapons.

Wright addressed the first-strike argument yesterday by saying that the United States "had never struck the first blow" and never would.

However, two other Democrats who attended an early-morning meeting with the president before his announcement took a less sanguine view of first-strike possibilities. Sen. Alan Cranston (D-Calif.), one of six announced Democratic presidential candidates, called the decision "an act of folly" that would put the MX in highly vulnerable silos in an unwise effort to show the Soviets that the United States is "tough."

Rep. Joseph P. Addabbo (D-N.Y.), chairman of the House Defense appropriations subcommittee, said the missile "makes no sense" except for first-strike use, and contended that it would be best "to kill the MX once and for all."

The administration nonetheless was pleased that Addabbo pledged to Reagan to bring the president's recommendation "expeditiously" to the House floor for an up-or-down vote. Under terms of a congressional resolution of last December Congress has 45 days to act on the president's recommendation, but both Wright and Addabbo predicted that action would come well before that deadline.

The action will come on a resolution appropriating funds to develop the MX and build extra protection for the 100 Minuteman silos plus engineering development funds for the small missile, which would weigh one-seventh as much as the 100-ton MX.

Total cost of the program, including development but not deployment of the small missile, was estimated at $19.9 billion, including the $4 billion already spent on research and development. This is $8 billion less than the estimated cost of the "Dense Pack" basing plan rejected by Congress last December, and Reagan said there would be as a result a $1.5 billion "savings" in the defense budget this year and other savings in the future.

In his meeting with congressional leaders this morning the president emphasized the arms control implications of the plan, especially important to the administration during a week when it faces an uphill battle to defeat a nuclear freeze resolution in the House.

"I cannot conceive the next generation facing the prospects of a future without an arms reduction agreement," White House spokesman Larry Speakes quoted Reagan as telling congressional leaders. "We will do everything we can and stay as long as we need at the bargaining table in Geneva to get arms reductions."

Reagan also emphasized the arms control theme in his statement, saying: "Unless we modernize our land-based missile systems, the Soviet Union will have no real reason to negotiate meaningful reductions. If we fail to act, we cannot reasonably expect an acceptable outcome in any arms control negotiation and we will also weaken the deterrent posture that has preserved the peace for more than a generation."

When the commission reported last week, its vice chairman, Thomas C. Reed, put it more bluntly, saying the proposal was not a bargaining chip in negotiations, and adding, "What is a bargaining chip is what we'll be doing if the Soviets don't come to the bargaining table."