Despite warnings that two new major social-welfare programs would require vast outlays at a time when White House and congressional negotiators on deficit reduction are scratching to save a few billion dollars, the House Rules Committee yesterday moved toward permitting floor votes on the initiatives.

By voice vote, the committee forwarded a Democratic welfare-overhaul measure that is projected to cost about $5 billion over the next five years.

"This bill involves enormous expenditures," said Rep. Hank Brown (R-Colo.), urging that the committee not allow a floor vote on the bill "while Congress is in the middle of negotiating a compromise" on budget cuts.

Brown said that in view of the large costs, "I think it's very clear that the president will veto the committee bill. If sustained, we've accomplished nothing."

Rep. Anthony C. Beilenson (D-Calif.), however, said of the Ways and Means Committee bill, "The truth is, for welfare reform to succeed, it's got to be expensive."

Rep. Thomas J. Downey (D-N.Y.), who helped craft the bill and is expected to lead the floor debate on it, noted, "The vast majority of welfare recipients are interested in working. They are not interested in staying on welfare . . . . We are about to educate and train women so they can go to work."

Brown argued that if the Rules Committee allows the bill to go to the floor, it should at least permit the Republican leadership to offer a substitute that would cost about $1 billion over five years, or an alternative worked out by Reps. Thomas R. Carper (D-Del.) and Charles W. Stenholm (D-Tex.) that would cost $2.5 billion over five years.

But the Rules Committee, with Chairman Claude Pepper (D-Fla.) wielding a stern gavel, approved the bill with authority for only one amendment, the GOP substitute. The Carper-Stenholm proposal will not be offered as an amendment unless supporters first defeat the resolution governing debate.

The three bills call for special work, training and education programs for mothers to get them off welfare rolls and onto payrolls. But the Ways and Means Committee bill also includes three major benefit increases -- mandatory benefits for two-parent families, inducements to the states to raise benefits, and a requirement that states allow welfare clients who have some earnings to keep a larger portion without loss of welfare benefits.

Republicans argued that the benefit increases would make it easier to live on welfare and avoid work, undermining the measure's work provisions.

On another social policy initiative, Pepper clashed with other Democrats on a proposal by Pepper and Rep. Edward R. Roybal (D-Calif.) to provide long-term home health and maintenance aid for all aged and disabled adults and children. The cost was estimated at about $25 billion over five years.

The money would be raised by eliminating the $43,800 cap on wages subject to the 1.45 percent Medicare portion of the Social Security payroll tax.

"It's an objective I've cherished for nearly 50 years -- comprehensive long-term care," Pepper said. He said that if a veto is threatened, he would visit President Reagan, have a "prayer service" and say, "You have a chance to do more than Franklin Roosevelt, to give them something he didn't -- health care."

The Pepper bill would cost five times as much as the Democratic welfare bill and has never been studied by the Ways and Means Committee, but Pepper fended off objections and said he will make the bill eligible for a floor vote. Pepper added that he won't force the bill to the floor until the Democratic leadership agrees, probably next year. Final committee action on the bill was postponed until today.

Ways and Means Chairman Dan Rostenkowski (D-Ill.) pleaded with Pepper to delay Rules Committee action until the bill had been evaluated by a special commission and by the Ways and Means panel.

"Sometimes you can't be as generous as you want to be. Christmas season is over as far as the Congress" goes, Rostenkowski said. "You'd better think a long time because these are big bucks involved in the Pepper bill."