Three senators injected the emotional abortion issue into the tax-overhaul debate yesterday, a move that could foil efforts by Senate leaders to speed the tax package through the chamber by the end of this week.

Gordon J. Humphrey (R-N.H.) announced that he and William L. Armstrong (R-Colo.) and Jesse Helms (R-N.C.) plan to introduce as early as today an amendment to the tax-overhaul bill denying tax-exempt status to institutions that finance, perform or provide facilities for abortions.

Humphrey said the measure could force more than 1,000 nonprofit hospitals and clinics to begin paying taxes.

The move threatened to touch off a divisive debate as the Senate began its first full week of deliberations on the dramatic proposal to revise the tax code. It also placed key supporters of the bill in a difficult position.

Majority Leader Robert J. Dole (R-Kan.), who has been urging senators to oppose major amendments and has opposed federal funding of abortions, was leaning toward supporting the amendment, according to congressional sources.

Sen. David F. Durenberger (R-Minn.), an opponent of abortion who strongly supports the tax bill, was said by an aide to be "at sixes and sevens."

Senate Finance Committee Chairman Bob Packwood (R-Ore.), a prominent abortion-rights advocate, strongly criticized the amendment last week as inappropriate to floor debate on tax overhaul.

Aides to Packwood emphasized that the issue was not brought before the Finance Committee during its 18 months of deliberation on the tax bill.

Several congressional aides said it is unclear whether the amendment will gather enough support to pass, but aides to Durenberger and others said that they are taking it seriously.

"It does have the potential to slow things down," a Durenberger aide said.

The amendment comes at an opportune time for opponents of abortion. The National Right to Life Committee is to open its national convention in Denver Thursday and, because Senate proceedings debuted on television last week, a Senate abortion debate would be broadcast nationally for the first time.

The amendment would raise about $30 million, according to Humphrey, by eliminating the tax-exempt status of many nonprofit hospitals that provide abortions, fund-raising foundations that aid those hospitals, and such organizations as Planned Parenthood, which operates and finances nonprofit abortion clinics.

The amendment has provoked wide national opposition, ranging from "pro-choice" groups to the United Way, the YWCA, the association of Junior Leagues and the National Council of Jewish Women.

Many of the groups see the measure as a threat to the concept of charitable, tax-exempt status because it singles out a single, legal activity as making an organization automatically taxable, officials of the groups said.

Humphrey sees it differently.

"Exempting an organization from taxes which would otherwise be due the Treasury is no different than disbursing funds from the Treasury to that orgnzation," he said in arguing for his amendment. "I wouldn't characterize the killing of innocent human life as charitable in any sense of the word."

Humphrey's announcement was among the few moments of controversy surrounding the tax bill, on which senators are expected to begin voting today.

Dole said he still sees the move to restore full benefits for Individual Retirement Accounts as the strongest threat to the bill.

He said that some senators may push for a sense-of-the Senate resolution asking that IRA benefits be restored in a House-Senate conference committee rather than on the Senate floor, where they could upset the delicate balance of loophole-closings and lower rates that has made the bill popular.