President Carter is pushing the arms race beyond the point of no return by opting for the MX blockbuster missile that could destroy Soviet strategic weapons, Sen. Mark O. Hatfield (R-Ore.) said yesterday.

Hatfield said he and like-minded senators will sponsor amendments and meetings in hopes of reversing the decision to build the MX, a weapon powerful and accurate enough to destroy Soviet strategic missiles in what is called a "counterforce" capability.

"Once you have moved from the present deterrent base," the policy of building a retaliatory force to deter the Soviets from firing their weapons in a surprise strike, switching instead to a counterforce arsenal, Hatfield said, "it becomes a fiction" to talk about future arms control agreements.

A White House spokesman for President Carter said last week that developing the MX would strengthen the U.S. hand in negotiating further reductions in a third strategic arms limitation treaty called SALT III.

SALT III, Hatfield said in an interview yesterday, "becomes an improbability if not an impossibility once the MX is deployed." He added that once both sides have deployed counterforce weapons, "You have introduced another dimension in foreign relations."

When the United States and the Soviet Union "get into flash points in places like the Middle East and Persian Gulf," argued Hatfield, and both sides have counterforce weapons deployed, "you have immediately introduced the possibility of preemptive strikes" as each side considers launching missiles for fear it would be destroyed by the other.

Hatfield said he made those and other points over the last several days with Secretary of State Cyrus R. Vance and Vice President Mondale in a vain effort to talk the administration out of going ahead with the MX.

Now that Carter has opted for the weapon, Hatfield said he and his allies will try to deny money for it, hold a series of meetings to point out the dangers of counterforce capability and then may seek to amend SALT II on the Senate floor.

If administration officials are backing the MX to placate Senate hawks and get their votes for SALT II, Hatfield said, "They're wrong to take it for granted that we're going to come along" and vote for the treaty despite the MX.