House leaders are expecting a close vote today when the issue of keeping the B1 bomber alive is taken up on the House floor.

The House leadership and other proponents of knocking out of a supplemental appropriations bill $462 million to build two more B1 prototype planes yesterday enlisted President Carter's last-minute help. Carter was expected to make about a half-dozen phone calls to key members before the vote.

About 50 House members were also invited to a breakfast yesterday with Defense Secretary Harold Brown. Appropriations Committee Chairman George Mahon (D-Tex.) and Rep. Joseph Addabbo (D-N.Y.), a leader in the fight to kill the money for the plane.

At President Carter's urging, both the Senate and the House had voted to cancel the B1 bomber program, though the House vote Sept. 8 was close, 202 to 199.

However, after that vote, Defense Department talk about funding an FB111 bomber as an alternative to the B1 angered many House members. That, combined with high absenteeism, caused the House to vote to include the $462 million in the supplemental appropriations on Dec. 6.

On Feb. 1 the Senate voted. 53 to 37, to uphold its position in favor of cutting the B1 funding out of the supplemental. If the House does not agree. the bill will have to go back to conference between the House and Senate.

One of the major arguments of those opposing the B1 is that extending it would tie up some $7.1 billion for other items in the supplemental.

But advocates of the B1 feel it is essential to build the two additional prototype planes in order to keep hopes of eventual production alive.