Cooling off the self-congratulation by supporters of a new INF treaty, Senate Republicans have quietly accused the administration of blocking the U.S.-Soviet review of the ABM Treaty due this fall because it might endanger ratification of the agreement -- not to mention embarrass Soviet leader Mikhail Gorbachev at the summit.

Nearly one-half of the 46 Republican senators, all of them defense-oriented and most of them conservative, wrote privately to President Reagan this week. Raising a barrier to ratifying an INF treaty, they said it would be ''a grave mistake'' even to seek Senate ratification until the new five-year review of the 1972 ABM treaty has been submitted to the Senate.

That warning goes to the heart of perhaps the most delicate question facing Reagan on the pending INF agreement: Will two-thirds of the Senate vote to ratify if the Soviet Union continues to violate the ABM Treaty, most notably with its almost completed radar at Krasnoyarsk?

At least 20 Republican senators signed the letter to Reagan, headed by the ranking member on the Foreign Relations Committee, Sen. Jesse Helms. That panel controls the ratification process. By no means are all signers decided at this point to oppose the treaty, which is due to emerge from the summit later this year that Reagan will hold with the Soviet leader.

One signer, Sen. Dan Quayle, says publicly he wants to support the treaty aimed at doing away with the entire class of superpower intermediate-range missiles. But Quayle told PBS's McNeil-Lehrer news program last week that the new treaty is a ''political treaty going along with an arms control process . . . with far more of a political rationale than a military one.''

Quayle authored the Senate resolution, passed 89-to-0 early this month, labeling the Krasnoyarsk radar an ABM Treaty violation. He and his Republican colleagues are convinced the administration is deliberately delaying the new review of the ABM Treaty, conducted by a joint U.S.-Soviet review panel in Geneva every five years, because of total failure to bring the Soviets into compliance.

If done in timely fashion as called for by the ABM treaty, the review's findings of continued Soviet violations would have to be reported to the Senate by Dec. 1. Hitting Gorbachev with a cheating charge just as he arrives for his cozy talks with the president would not make for jollier times at the summit.

But the GOP letter has a deadly serious rationale. Discovery of the illegal Krasnoyarsk radar was made possible by space photography of an immense array of buildings and assembly areas the size of three football fields in Siberia. Sooner or later, a U.S. ''image'' satellite was all but certain to discover it.

Not so, however, with the several hundred small intermediate-range missiles that Gorbachev will promise to destroy under the INF treaty. The United States neither has nor could have any idea where all these missiles are. They are easily concealed from cameras. One top administration official told us: ''The number of unaccounted-for SS-20s {the main Soviet weapon to be destroyed} is not trivial. It is high enough to be highly embarrassing some time in the future''.

Hence the importance of the charge in the Republican senators' letter to the president. It ties the existing Soviet cheating on the ABM Treaty, comparatively easy to discover, with the task of overseeing compliance with the INF agreement, an impossible goal that no army of on-site U.S. inspectors crisscrossing the Soviet Union could reach. The letter in effect warns that unless Moscow shows good faith by ending its violations of the ABM treaty, the United States should never risk noncompliance with an unenforceable INF agreement.

The letter to Reagan also charged that a ''purported new violation'' of the ABM Treaty has been discovered recently by the administration. That is another reason, it says, for not delaying the five-year ABM review.

Secretary of State George Shultz and key White House aides oppose these sensible suggestions, wanting no waves on the way to the summit. But there may be regrets when the INF treaty hits the Senate floor. In a barely noticed Senate vote last week, 25 Republicans (not matching signers of the letter to Reagan) voted with three Democrats against ratifying an INF treaty until Reagan certifies full Soviet compliance with the ABM Treaty -- among them Senate minority leader and major presidential aspirant Bob Dole.