Battle for House defense-panel chair. Four Democrats campaign for leadership of influential panel

One candidate is a defense intellectual who flouts precedent and raises hackles. Another is described by colleagues as a cantankerous loner who has, nonetheless, compiled a strong record in his 38 years in the House of Representatives. A third hopeful is a popular team player and dealmaker and former mayor of a small Massachusetts city. The fourth is a leading Southern ``Boll Weevil'' conservative Democrat who has eagerly supported the Reagan revolution.

The careers of Democratic congressmen Les Aspin of Wisconsin, Charles Bennett of Florida, Nicholas Mavroules of Massachusetts, and Marvin Leath of Texas intersect Thursday when House Democrats elect one of them to be the chairman of the Armed Services Committee.

The post is one of the most influential on Capitol Hill, and the victor will play a major role in shaping United States defense policy. Thus, the race for the chairmanship has developed into one of the most bitter House conflicts in recent history.

``This has resulted in horrible divisions,'' says Mr. Mavroules. ``Whoever wins will face hard, hard feelings, and it will take a while to bring them back.''

There are several reasons why Mr. Aspin, the committee's chairman during the last Congress, faces a serious challenge. Many House Democrats oppose some of Aspin's positions - for example, his unexpected votes in favor of the MX ballistic missile and aid to the Nicaraguan contras. And Aspin's sometimes brusque style rubs some colleagues the wrong way.

Their anger is compounded by the fact that two years ago an alliance of moderate and liberal Democrats ejected Rep. Melvin Price (D) of Illinois as the committee's chairman in favor of Aspin. Democrats said they allowed Aspin to skip over the heads of six more senior Democrats, despite the objections of then-House Speaker Thomas P. O'Neill Jr., on the assumption that he would better represent the views of Democrats on the committee.

Nonetheless, most observers thought that Aspin, who is considered an effective Democratic spokesman on defense issues and a competent administrator, would narrowly survive the challenge.

On Jan. 7, however, House Democrats voted 130-124 to oust Aspin from the chairmanship. The race for a successor was on.

Candidates and their supporters in the House have lobbied strenuously, largely through telephone calls to their out-of-town colleagues. ``I've got a three-inch callous on my ear,'' jokes Mr. Leath, who calls his campaign strategy ``one-on-one-on-one-on-one.''

Leath is considered the front-runner in the race, followed by Aspin, Mavroules, and Bennett. But even the most experienced nose-counters cannot predict which way the final tally will run. The winner must receive an absolute majority of votes cast, not just a plurality.

Complicating the choice for many members is the confused politics of this race. Leath, one of the most conservative members of the Democratic caucus, bills himself as ``the consensus candidate'' and has compiled a list of supporters of wide ideological diversity. Leath admits he will have to move to the left in his positions, and he won plaudits from Democrats for opposing Reagan administration defense budget requests last year on the House Budget Committee.

But the prospect of Leath's heading up the House Armed Services Committee, while the Senate Armed Services Committee is headed up by conservative Sen. Sam Nunn (D) of Georgia, leaves many Democrats wondering whether the views of liberal Democrats will get short shrift when it is time for the two chambers to bargain over the size and shape of the defense program.

Bennett was skipped over when Aspin became chairman two years ago. By the terms of the seniority system, he is most eligible of the four to become chairman. Ideologically he is in tune with his colleagues. But his sometimes iconoclastic personal style and his age relative to the other candidates count against him.

Mavroules, who boasts a consistently liberal voting record and is well liked by his colleagues, began campaigning after Leath and Bennett had been sewing up commitments for months.

That leaves Aspin. Even his most vehement opponents concede that Aspin, the holder of a PhD from the Massachusetts Institute of Technology, is the brightest of the candidates. Others fear that by removing Aspin, only two years after removing Mr. Price, lawmakers will set a precedent that could straitjacket future chairmen.

Yet many believe that Aspin would have such a weak mandate from his colleagues that the same threat would rise again in two years, thus limiting his effectiveness.

``It's all going to happen again'' if Aspin is reelected, says Bennett. ``It's time to put this whole thing behind us.''