The F.E. Warren Air Force Base, which is headquartered at Cheyenne, Wyo., and spreads into Colorado and Nebraska, is the leading contender to house the first 40 new MX intercontinental missiles, according to congressional and Pentagon sources.

Rep. Virginia Smith (R-Neb.) reported to her constituents in a weekend press release that she had been told by Air Force and Pentagon officials that Warren "is the most logical selection" as a base for the initial batch of MX missiles in existing Minuteman missile silos. By mid-1983, the Pentagon is supposed to figure out where to base the planned 100-missile MX force permanently.

Other possible sites include Ellsworth Air Force Base in South Dakota, where other Minuteman silos are scheduled for improvement anyway, and Grand Forks Air Force Base in North Dakota. But several officials say that the geological conditions at Warren are the most favorable, citing the resistance of the ground and the bedrock surrounding the silos to shock from the atomic blast of attacking missiles.

The United States has 1,000 Minuteman missiles spread over seven bases, and 200 of the most advanced version, the Minuteman III, are based at Warren.

Defense Secretary Caspar W. Weinberger reportedly is scheduled to make the base decision March 8, though sources say the Air Force and the Pentagon have not yet made their presentations to him. While Warren has technical advantages, the fact that the base sprawls over three states could bring more political problems than another selection.

Sources also say that just-completed Pentagon studies have led to a happier conclusion about the degree of "hardness" or resistance to atomic blast of the Minuteman silos. Because MX is a bigger missile than Minuteman, it was feared that the switch would actually increase the danger to MX because it would have less "rattle room" inside the underground silo to absorb shock.

But new studies show that because the MX missile is in its own canister as well as in the silo, the use of stiffer shock-absorbing materials can keep the level of hardness about the same as it is with the existing Minuteman force.

Initially, the administration had planned to put the first 40 or so MX missiles in old Titan silos and "super-harden" those silos with more concrete and steel, but that plan has been dropped.