The Carter administration is facing a concerted congressional political attack on its new strategic arms agreements with the Russian, and proponents now concede that Senate approval of the pacts is in doubt.

The political attack led Sen. Henry M. Jackson (D-Wash.) and his staff - is not the only reason the new arms pacts are in trouble, according to Senate and administration sources. They also blame the administration's overall political standing, which currently is not strong, and its inability thus far to make a strong ease for the new agreements, which are still being negotiated in Geneva.

Many sources in the Senate say there is a plausible chance that Jackson and his allies could convince 34 senators to vote against a new arms control treaty, thus preventing its ratification, dramatically disrupting Soviet American relations and perhaps igniting a multibillion-dollar round in the arms race.

Sources close to Jackson acknowledge he is extremely unhappy with the pacts as outlined thus far and is trying to persuade the administration to go back to the Russians and ask to renegotiate aspects of them.

Jackson insists he is trying to act "constructively," and denies he already opposes the new agreements. But he adds that he'll know "in a week or so" whether the administration has agreed to try to improve on the agreements before submitting them to the Senate - apparently a warning.

Administration officials charge that Jackson and his influential aide, Richard Perle, have manipulated news accounts and otherwise planted seeds of doubt and distrust around Washington in hopes of disrupting or drastically altering administration policy.

A key Senate aide sympathetic to the administration and its new arms control agreements said their chances "are in the 50-50 range right now."

Several knowledgeable sources argued that Jackson's goal may not be rejection of the new pacts, but some sort of rider or sense-of-the-Senate resolution trying the administration's hands for the next round of Strategic Arms Limitation Takes (SALT).

The political situation evolving around the new SALT agreements is almost as complex as the agreements themselves, details of which have been leaked and have appeared in news accounts. There will be disputes not only about the content of the pacts, but about the way they have been negotiated.

The administration and its allies in the Senate will argue that the new agreements are good ones, containing significant Soviet concessions, numerical equality between the superpowers and new sources of stability in the arms race. Jackson and other opponents can be expected to criticize the agreements as too generous to the Soviets, too difficult to verify and too far removed from the administration's previous statements on what new agreements should contain, among other complaints.

Both sides acknowledge that there are at least 20 to 25 senators who will vote against the agreements, almost regardless of what they say, and about 40 who can be expected to vote for them. That leaves about 35 senators who will decide the outcome.

They will have to vote on a complex package whose final contents are still being worked out. The key elements of the package are:

A new SALT treaty to remain in effect until 1985, which will provide new numerical limits to both countries' strategic arsenals.

The first SALT agreement on offensive weapons allowed the Soviets more than the Americans, partly as a compensation for superior American technology. The new treaty allows equal numbers to both.

It limits both to about 2,200 strategic missiles - based either on land or in submarines - and intercontinental bombers. Of those, 2,200 or so, 1,320 can be equipped with multiple warheads - independently targetable atomic weapons, which means that warheads carried by one missile can destroy three to 10 targets . Of that 1,320, 1,200 can be land or sea-based missiles, so 120 can be a new kind of weapon that only the United States can now deploy - intercontinental weapons armed with numerous, independently targetable cruise missles. The Soviets apparently have not started to develop cruise missiles.

Another limitations in the new treaty is on the deadliest weapon in the nuclear arsenal, the land-based missile with multiple warheads. These are much more accurate than submarine-based missiles, so there is at least a theoretical possibility that land-based missiles could be used to launch a first strike - the greatest danger of nuclear war, according to many strategists.

The new treaty will limit both countries to 820 land-based missiles with multiple warheads.

A three-year protocol will accompany the treaty. Its purpose is to put some controls for the first time on the qualitative improvements of the two countries' weapons systems.

Details of the protocol are being worked out. It would limit or forbid fight tests of new kinds of missiles, though there is no agreed definition yet of what a "new" missile is. It would prohibit deployment of new weapons systems. It would limit the range of air-launched cruise missiles to about 1,800 miles, and the range of sea and land-launched crusie missiles to about 360 miles.

The Soviets will agree not to increase production of the Backfire bomber, a disputed weapon Moscow says it not strategic, but the Pentagon thinks could be used to bomb the United States. The Soviets also will give certain assurances about the deployment and refueling of Backfires in tended to demonstrate that they will not be used as intercontinental bombers.

A statement of principles will be published to accompany the treaty and protocol. This will announce the superpowers' intentions for the next round of arms-reduction negotiations, including a joint commitment to negotiate substantial, mutual reductions in strategic weapons by 1980.

As President Carter indicated at his press conference yesterday, completion of the three documents probably will take several months.

Here are some of the arguments that will be made in the Senate for and against provisions of the new agreements:

It is too soft - much less demanding on the Soviets than the "comprehensive proposal" Secretary of State Cyrus R. Vance took to Moscow in March.

Jackson and his camp will argue that the new agreements do not measure up to the contents of the March proposals or the rhetoric the administration used then to defend them. Those proposals would have put more severe limits on the Soviets' weapons, including their largest land-based missiles, which are not specifically controlled in the new agreements.

Specifically, the Jackson camp believes that the new agreements' limits on Soviet land-based missiles are too high and thus endanger the survivability of the United States' 1,040 land-based Minuteman missiles in the event the Soviets attacked them.

The administration and its Senate supporters will respond that the March proposal is not a sensible standard of comparison, since the Soviets rejected it brutally. The better standard, they argue, is the December, 1974, agreements reached at Vladivostok by President Ford and Soviet leader Leonid I. Brezhnev.

Compared to Vladivostok, friends of the agreements argue, the new pacts are move favorable to the United States and to stablility in the arms race.

As to Minuteman vulnerability, they will argue that the American land-based missiles were vulnerable under the terms of Vladivostok, remained vulnerable even under the terms of the rejected March comprehensive proposal and are still vulnerable. The agreements cannot resolve all the problems posed by the balance of terror, an administration official said.

The administration acknowledges that the new pacts do not live up to all the rhetoric used last spring in defense of the comprehensive proposal. Officials expect some embarrassment and political difficulty on this score.

Too much in the agreements cannot be verified. The Jackson camp says the Soviets can make too many improvements in their missiles and can continue development of new weapons too easily under the terms of the new pacts. At the end of three years, when the protocol expires, the Soviets will be well-placed to improve dramatically their weapons systems, sources close to Jackson argue.

Jackson and his associates recall with evident satisfaction one quotation fron the stormy confirmation hearings of Paul C. Warnke to be the chief U.S. arms control negotiator. On the occassion Warnke said: "I think . . . that an agreement which is not verifiable is worse than no agreement."

Supporters of the pacts will counter that the important limits on intercontinental missiles in the treaty are verifiable, and that the impossible of verifying range limits and deployments of cruise missiles poses a practical problem only for the Soviet Union, not for the United States, since only the United States has cruise missiles.

Limitations on land-based cruise missiles are foolish because the United States and its European allies need them badly to re-establish a reliable military balance in Central Europe. Moreover, by accepting these limits, it is being argued, U.S. negotiatiors have allowed a European-based weapons system to become a pawn in negotiations previously restricted to intercontinental strategic systems.

This is an esoteric point laymen, but could carry substantial weight with some senators, particularly Sam Nunn (D-Ga.), whose special concern is NATO and Central Europe. The unmanned cruise missle has been seen as a potentially effective tactical and strategic weapon for NATO forces in Europe.

Friends of the agreements will reply that the Europeans are pleased with the pacts - administration officials insist they are - and that the United States can continue developing cruise missiles under the protocol. These new weapons couldn't be ready in fewer than three years in any case, the length of time the protocol will remain in force, the administration will argue.

The new pacts allow the Soviets too free a rein in regard to their Backfire bomber. Sovurces close to Jackson note that the Joint Chiefs of Staff have taken the position that the sorts of controls on Backfire contained in the new pacts are inadequate.

Administration sources and others in the Senate friendly to the pacts acknowledge that the Backfire dispute is not resolved by the new pacts, but insist that it is much less significant than the overall limits.

The administration's supporters all seem to agree that the best case they can make for their new agreements is "the big picture," in the words of one Senate aide. "They have better arguments than they have yet made," said another Senate aide, who expressed dismay that the Preisdent has not decided what the key elements of the situation are and who best to express them.

Jackson and his associates will dispute the administration version of that big picture but they are likely to concentrate on details of the pacts and the way they were negotiated, partly to suggest or demonstrate that the American side botched the negotiations and got fewer Soviet concessions than it could have.

Sources in the Jackson camp make no secret of their distrust of Warnke and Leslie H. Geib, the State Department official most intimately involved in the SALT talks. These sources have passed the word that Vance was ill-informed during two appearances before Jackson's Armed Services subcommittee last Friday and the Friday before, and that Jackson and others repeatedly embarrassed him with difficult questions.

The administrations' allies bemoan the fact that Carter seemed to build to Jackson's role in the SALT process last spring by visibly consulting him often and drafting the March comprehensive proposals to the Soviets largely from a 23-page memorandum prepared by Jackson.