House Speaker Thomas P. (Tip) O'Neill Jr. (D-Mass.) and Senate Majority Leader Howard H. Baker Jr. (R-Tenn.) are considering a proposal to delay a vote on further production of MX missiles until after the Nov. 6 elections as part of a compromise on defense spending for next year.
While the two leaders have not agreed on any aspects of a compromise, sources confirmed yesterday that they are exploring a delay as one element of an accord to break a weeks-long deadlock on the defense program for fiscal 1985.
The sources also said that at least some White House officials have indicated new flexibility on the defense issue, essentially affording what one called limited "running room" for Baker to negotiate an agreement.
But they cautioned that the negotiations are extremely delicate and that any one element hinges on the whole package. It could fall apart, they said, if there are objections from either the administration or other congressional leaders, who are expected to be asked to review any O'Neill-Baker proposals.
There were conflicting signals yesterday from the White House on the MX issue, which congressional and other sources said pointed to a split between the so-called legislative pragmatists and President Reagan's national security advisers.
While one official suggested that the administration would be willing to compromise on the MX if it got enough money for defense in general, another indicated that the White House was standing firm on the MX and overall defense spending.
"The Democrats want to make it a partisan issue and try to wear us down . . . ," said the second official. "We are not going to play that game."
Although the Democratic-controlled House and the Republican-controlled Senate have staked out sharply divergent positions on continued production of the huge, costly new intercontinental ballistic missile, they did so by close votes in connection with the fiscal 1985 defense authorization bill earlier this year.
In a series of cliff-hanging votes in late May, the House voted to defer production of more MXs until April, when Congress would have to vote again on whether to authorize 15 additional missiles. The margins were no larger than three votes on each roll call.
In an even closer call two weeks later, the Senate voted to go ahead with production of 21 more missiles, with no strings attached, but only after Vice President Bush broke a 48-to-48 tie to save the MX from a year-long production moratorium.
Since then, Senate Republican leaders have stalled a vote on a defense appropriations bill for fiscal 1985, largely out of fear that MX foes have gained enough votes to pass the moratorium.
Neither the House position nor the Senate's would affect production of the 21 MX missiles Congress approved for this fiscal year, and some lawmakers argue that a delay until April would not seriously disrupt the missile's production.
Some legislators have suggested privately that the MX would fare better in Congress after the Nov. 6 election, especially if Reagan wins by a big margin over Democratic presidential nominee Walter F. Mondale, who opposes the missile. But others contend that MX support has been on a slide that could be accelerated by even small Republican election losses in the Senate.
According to aides in both houses, a key sticking point on the MX deferral issue is whether to ban further production of the missiles unless Congress votes to authorize them or whether to let the production go ahead unless Congress votes to disapprove it.
This could be critical if Reagan wins reelection because he would almost certainly veto a disapproval measure, thereby requiring a two-thirds vote of both houses to overcome the veto. By contrast, it would take only a majority vote of one house to block a new authorization. Democrats rejected the disapproval-vote proposal in the defense authorization conference and say Baker will have to agree to a new authorization vote if he wants a deal.
By wrapping all defense issues into the negotiations, the Republicans can use an MX deferral to try to ratchet up and lock in the overall defense spending number, which GOP aides described as the administration's main concern.
Until now, at least, the White House and Senate Republicans have stood firm behind their "Rose Garden" agreement for $299 billion for defense next year, an increase of nearly 8 percent over fiscal 1984 after accounting for inflation.
In its budget for next year, the House approved $285.7 billion for defense, an after-inflation increase of 3.5 percent, although House leaders have indicated they would accept $292.2 billion, an increase of about 5 percent.
One usually well-informed source said yesterday that the White House "pragmatists" were willing to accept an MX delay in exchange for $297 billion for defense. But this was said to be unacceptable to the national security group.