Anti-abortion forces in the Senate, beaten back last year in their attempts to restrict legalized abortion, were presented yesterday with yet another rallying point.

Sen. Thomas F. Eagleton (D-Mo.) testified that a new, 10-word, proposed constitutional amendment that he drafted "may be the most politically feasible yet meaningful step Congress can take toward promoting the fundamental right to life of the unborn."

The amendment would reverse Roe vs. Wade, the 1973 Supreme Court decision legalizing abortion nationwide, by stating: "A right to abortion is not secured by this Constitution." That would make abortion, as it was before 1973, legal in some states and prohibited in others.

Sen. Orrin G. Hatch (R-Utah), an anti-abortion leader, said he agrees with Eagleton and may allow the amendment to be substituted for a more restrictive proposed constitutional amendment that Hatch championed last year.

Eagleton's proposal could become the key Senate vehicle for debate on abortion because Hatch has a promise from Senate Majority Leader Howard H. Baker Jr. (R-Tenn.) to be allowed to bring a constitutional amendment to the Senate floor this spring.

But such a move could set off the same kind of divisiveness that split anti-abortion forces last year. President Reagan and several key anti-abortion legislators have endorsed a competing measure, written by Rep. Henry J. Hyde (R-Ill.).

In marked contrast to the lengthy, volatile hearings and debate in the last Congress, Eagleton's amendment was discussed at a short, low-key hearing of the Senate Judiciary Committee's Constitution subcommittee, which Hatch heads.

Sen. Bob Packwood (R-Ore.), a leading pro-abortion spokesman, testified at the first of two days of hearings that anti-abortion forces have become desperate because they "know full well that every day, every week, every month, every year, time is against them."

"If they do not get it a victory in this Congress, I think they are finished and I think they know they are finished," he said.

Packwood, leader of a filibuster against proposed anti-abortion legislation last year, said he is prepared to "do everything I can, tooth and toenail, to stop it the amendment from being passed."

Congressional passage of a constitutional amendment requires a two-thirds majority vote in each house before the proposed amendment can be sent to the states for ratification. Spokesmen for groups for and against abortion yesterday said they doubt any amendment could muster that much support in this Congress.

Hyde's bill requires only a simple congressional majority vote for passage.