The future of Interior Secretary James G. Watt remained uncertain over the weekend, as the White House monitored political fallout from his latest controversial remarks and conservative and moderate Republicans split over whether his departure would hurt or help the GOP in the coming election year.

As pressures built for President Reagan to decide, White House officials were expected to confer this week with Senate Republican leaders on their reading of whether Reagan can afford to continue backing his most conservative Cabinet officer despite Watt's characterization of five advisers as "a black , . . . a woman, two Jews and a cripple."

Assistant Senate Majority Leader Ted Stevens (R-Alaska) of the GOP's conservative wing fervently defended Watt yesterday as a "God-fearing man" and vowed to block a proposed Senate resolution calling for his resignation.

The resolution, sponsored by Senate Minority Leader Robert C. Byrd (D-W.Va.), is to come to the floor Wednesday, and, in light of calls for Watt's ouster by 10 GOP senators, is expected to pass if brought to a vote.

"The way [the remark] came out was offensive," Stevens said on "Face the Nation" (CBS, WDVM). But he added: "What he did, was it offensive to get a commission . . . representing the minority groups? . . . . Are we really going to fire one that makes a mistake when he's doing the job he's been asked to do?"

Stevens' stand marked a break in the ranks of the Senate leadership, most of whose members have joined Democrats in sternly denouncing Watt for his remarks last week about the commission investigating his embattled coal-leasing program.

Majority Leader Howard H. Baker Jr. (R-Tenn.), Finance Committee Chairman Robert J. Dole (R-Kan.) and Budget Committee Chairman Pete V. Domenici (R-N.M.) have called Watt a liability to the administration and the Republican Party, contending that his effectiveness has seriously eroded. Dole told Watt by telephone Friday that he believes the secretary should resign.

Sen. Bob Packwood (R-Ore.), chairman of the Commerce, Science and Transportation Committee, also appearing on "Face the Nation," said that Watt should go and that Reagan, in not firing him, has missed an important chance to show sensitivity to minority groups.

"Honest people can disagree about [Watt's] environmental policies," Packwood said. " . . . But it is not permissible to go around making . . . demeaning statements about almost every group in America. Why do we have to put up with this liability that does us no good, has got nothing to do with the environmental policies, and all it is, is an insulting embarrassment?"

Republican National Committee Chairman Frank Fahrenkopf called Watt's comment "inexcusable," the same term used by Democratic presidential contender Walter F. Mondale at an Americans for Democratic Action meeting here yesterday. But Fahrenkopf said the statement alone should not force Watt out.

Reagan, who accepted a written apology from Watt on Thursday as adequate, remained silent on the matter yesterday. White House spokesman Larry Speakes said, "I know of no change in the Watt situation. Situation stable."

One factor being considered by the White House is a possible backlash by grass-roots conservative groups, who in the past have backed Watt enthusiastically. Richard A. Viguerie, one of the key fund-raisers from this group, said he is considering a direct-mail campaign to 2.5 million conservatives to try to pressure the White House to keep Watt.

"I think conservatives are looking at this decision of the president as a test of whether he keeps one of the few conservatives left in his administration," Viguerie said. " . . . This is a very warm, decent, compassionate man. He should be pointing the finger at the opposition out there, the liberals, the Democrats, primarily, who are . . . more concerned about the criminal than the victim." Watt's spokesman, Douglas Baldwin, yesterday said the secretary has received "quite a number" of telegrams and calls from supporters urging him to stay. He added that Watt received an award in 1981 for his efforts to make national park facilities more accessible to the disabled.