As Helms cries 'Marxism,' GOP maneuvers to back King holiday

New Right leader Jesse Helms has won a small victory as he digs his trenches to prevent creation of a national holiday for Martin Luther King Jr. The veteran of many one-man battles, Senator Helms has managed to delay a final vote on the proposal, probably until after Congress returns Oct. 17 from the Columbus Day break. But the North Carolina Republican's success will probably be short-lived because his opponents are not only Democrats, but members of his own party, who are scrambling to show that they are sensitive to civil rights.

While Helms denounced the slain civil rights leader's ''action-oriented Marxism'' and stopped just short of calling him a communist, Republicans were rushing to erase the image that their party agrees with him.

Senate majority leader Howard H. Baker Jr. (R) of Tennessee is wielding his leadership authority to keep control of the bill, which he has promised Dr. King's widow, Coretta Scott King, to support. ''He's going to do all he can to get it passed,'' says a Baker aide.

The majority leader bypassed the usual committee hearings by putting the bill directly on the Senate calendar, and he has already filed a petition to cut off debate. And while Helms has prevented final action on the proposal this week, the ranks of his supporters are thin.

Moderate Republicans, from Sen. Robert Dole of Kansas to Arlen Specter of Pennsylvania and Pete V. Domenici of New Mexico, have planted themselves firmly in the camp of supporters for the holiday, which would be celebrated on the third Monday in January beginning in 1986. Even conservative Sen. Strom Thurmond (R) of South Carolina supports the bill, and the White House indicates President Reagan will sign it.

''Republicans are used to being presumed guilty'' for not backing civil rights, says a GOP political official. ''If they're a little skittish, it's understandable.'' He is skeptical, however, that supporting the holiday will be much of a factor for the GOP in the coming Senate races.

An assistant to Senator Domenici says Republicans have ''been looking for something to do for black recognition, and this is a relatively easy one.'' But he doubts the action would boost minority affection for the GOP, which now attracts less than 10 percent of blacks.

The gesture may also emerge somewhat tarnished by the Senate debate, which has so far centered on emotional issues. In language reminiscent of the 1950s, Helms charged on the Senate floor that ''King's patterns of associations and activities show that, at the least, he had no strong objection to communism.''

Resurrecting reports from the now-defunct Committee on Un-American Activities , he charged that King, who once headed the Southern Christian Leadership Conference, ''apparently harbored sympathy for Marxism, at least in its economic doctrines, from the time of his education in divinity school.''

Sen. Edward M. Kennedy (D) of Massachusetts shot back that such charges were ''raised first and most vigorously by the arch-segregationists'' and said of the Helms remarks, ''I will not dignify them with a reply.''