FOR THE SECOND time in recent weeks, the administration has run up against congressional resistance to additional Pentagon spending. Last week, the president was defeated in his request for a $2 billion increase for the rest of this fiscal year when Congress overrode his veto of the supplemental appropriations bill. This week, the argument is over administration resistance to going along with 1983 defense spending limits set in the budget process.

From the perspective of Senate Republican leaders, much more is at stake than the defense budget itself. There is, of course, room for doubt that the administration's defense strategy is so finely honed that a few billion dollars can be crucial to its success. Nor has the administration made a case that any particular cut cannot be tolerated. But the issue that has given pause to so staunch an administration supporter as Sen. Ted Stevens, chairman of the Appropriations subcommittee on defense, is whether the administration is a reliable partner in congressional efforts to control the budget.

The budget resolution that Congress and the administration signed off on last June called for trimming several billion dollars from the amount the president wanted for defense in 1983. This year, Congress put very strict controls on the appropriations committees to make sure that the bills written for each program area stayed within the limits of the budget resolution. The final allocation agreements for each committee were made public in late July.

On Aug. 3, OMB Director David Stockman told the Senate Budget Committee that the administration not only agreed to those allocations -- including defense -- but would use them as the benchmark against which to judge whether the president should veto an appropriations bill. Now the administration claims that it did not understand the implications of the allocations, and Defense Secretary Weinberger has refused to supply a plan to meet the lower target.

The administration apparently hopes that by taking a hard line with Congress -- which has always found it hard to deal with the defense budget in other than pork-barrel terms -- it will win out in the rush to keep the government operating while Congress adjourns to prepare for the November elections. For example, the Appropriations Committee might agree to defer a decision on certain spending areas, report out a bill that appears to be within the budget limits and then put the extra money back in a supplemental bill next year.

Senate leaders, however, have good reason to push for a compromise that conforms with both the spirit and the letter of the budget resolution. If the agreement on defense spending is violated, control over congressional decisions in other parts of the budget will be greatly weakened. Congress will also have relinquished the only real leverage it has to persuade the administration to develop a coherent strategy for improving the nation's defenses without imposing intolerable strains on the federal budget.