To save his defense budget and undercut the nuclear freeze movement, President Reagan soon will have to accuse the Soviets publicly of violating arms control agreements with the United States, Sen. James. A. McClure (R-Idaho) said yesterday.

"He is inexorably being pushed into this," McClure said.

The senator told reporters that he saw his role as preparing the public for disclosures he expects Reagan to make soon.

"It's an open-and-shut case" that the Soviets have been testing two new intercontinental ballistic missiles, McClure said. The observed, though unratified, strategic arms limitation treaty (SALT II) permits tests of only one new missile.

McClure charged the Soviets with a long list of other arms control violations in a Senate speech Thursday.

The White House has said that the administration is preparing its case on alleged Soviet treaty violations, but has given no date for its public release. Asked yesterday why Reagan is reluctant to charge violations if they are clear, McClure blamed the government arms control bureaucracy, saying it did not want to endanger negotiations with the Soviets.

McClure said the administration should have raised the violations "more aggressively" in the Standing Consultative Commission established under SALT I.

William E. Jackson Jr., an arms control official in the Carter administration, said yesterday that "If the Reagan administration had been serious about holding the Russians to SALT II, it would have permitted its representatives at the SCC to raise SALT II compliance questions with the Russsians and to receive questions from the Russians about our own weapons programs." He said this week's recommendation by the MX advisory panel to deploy two new missiles, the MX and a smaller one, raises the question whether the United States would be violating SALT II.

McClure in his Senate speech said Soviet actions "of greatest concern" from the standpoint of living up to SALT II "have been rapid reload and refire exercises of the SS18 missile; concealed deployment of banned mobile SS16 missiles at the Plesetsk Test Range; deployment of long range air-to-surface cruise missiles on TU95 Bear intercontinental bombers and on Backfire bombers; almost total encryption of the telemetry associated with the testing of all significant missiles; development of two new types of ICBMs intercontinental ballistic missiles ; testing of a new mobile air defense system, SAM12, in an anti-ballistic missile mode; further increased strategic camouflage, concealment and deception" to hide weaponry from U.S. satellites; "evidence of direct attack" on a U.S. satellite "with blinding laser radiation . . . . "