HOUSTON, FEB. 12 -- The Houston Astros committed the Astrodome for the 1992 Republican Convention without approval of the National League and intend to leave the stadium for virtually a month, baseball officials said today.

Astros Chairman John McMullen, who is trying to sell the team, said the Astros are considering playing part of their 1992 home schedule at the Superdome in New Orleans, which lost out to Houston in bidding to host the Republicans.

National League Rule 2.1 requires all stadiums to give precedence to baseball. Philadelphia Phillies President Bill Giles said approval was not sought from NL ownership and a baseball official, speaking on condition of anonymity, said permission for a one-month rental was not asked of the league office.

The 1992 convention is scheduled for Aug. 17-20, but GOP officials have reserved the Astrodome for four weeks, July 27-Aug. 23, to prepare the site, etc. The Houston Sports Association, which owns the Astros and has control of the Astrodome lease, agreed to the city's proposal to host the convention.

The Major League Baseball Players Association said in New York it would not permit either a lengthy road trip or the Astros playing home games in another city.

The Astros played 16 August home games in 1990, their busiest home month of the season. Fifteen games are scheduled in the Astrodome for this August.