The Carter administration gave its cautious support yesterday to a congressional drive to kill off redundant or "low-priority federal programs through "sunset" legislation.

Backed by more than half the members of the Senate, the "sunset" bill would require review of virtually every federal program and income tax preference every five years, and would automatically terminate any that did not survive searching scrutiny.

Jimmy Carter heartily endorsed that bill during last fall's election campaign. But his administration witnesses leading off Senate hearings yesterday hedged their support with so many requested changes that sponsors were not sure whether they had helped or hurt the cause.

"Well, they're certainly cautious," said Sen. Edmund S. Muskie (D-Maine), after Bert Lance, director of the Office of Management and Budget, and Treasury Secretary W. Michael Blumenthal completed two hours of "yes, but" testimony before Muskie's Governmental Affairs subcommittee. "Our challenge," he said, "is to make them more positive."

The "sunset" bill - which was approved by the full committee last year but never reached a floor vote - has 54 sponsors in the Senate this year.

It would require legislative committees to evaluate all the government programs in a particular area every five years and would automatically kill off those not re-enacted.

The tax-writing committees of Congress would be required to make the same review at five-year intervals of each so-called "tax expenditure" - tax breaks for individuals, industries and other groups.

Muskie and the other members of the subcommittee, Sens. John Glenn (D-Ohio) and William V. Roth, Jr. (R-Del.), said "sunset" would serve Congress in much the same way that zero-base budgeting would serve Carter - as a device to eliminate overlapping, unproductive programs.

But Blumenthal counseled" extreme caution" in applying "sunset" to tax provisions, saying his Treasury experts had not figured out any way to make the scheme workable and warning that the threat of automatic extinction of hundreds of tax breaks might add to the "uncertainty" of investors and consumers.

And Lance said the provisions of the bill creating a new "Hoover Commission" and requiring transmission of voluminous budget-making data to Congress were either unncessary or "unworkable."

Blumenthal warned that he would have to come to Congress for a "significant increase" in Treasury employees if the bill became law, and Lance cautioned that "the cumulative result of these ("sunset") provisions may overload the executive branch with requests at the same time that it is attempting to carry out the annual zero-base budgeting efforts."

Muskie and Glenn strongly resisted Blumenthal's efforts to exempt, the "tax expenditures" from the reach of the "sunset" law, but Roth said he agreed with the Treasury Secretary on the hazards of including them.

On the other hand, Roth, as the principal proponent of the new "Hoover Commission" on government reorganization, objected to Lance's efforts to knock that section out of the bill.

All three senators tangled with Lance over his disinclination to give Congress automatic access to the budget requests that agencies send to OMB for the President's consideration.

Both Lance and Blumenthal softened their criticism with reiterated assurances that the Carter administration really does want "sunset" legislation passed by Congress this year.

But Glenn, at one point, felt called upon to read a lengthy passage from a Carter campaign speech in Columbus last fail, in which the Democratic nominee raked the Ford administration for being "lukewarm" about "sunset" legislation and vowed to give it his full support.

"I don't think I need to tell you who said that," Glenn said pointedly to Blumenthal.

"I know and I agree with every word of it," Blumenthal replied.