Washington ? Spurred by the high-profile killing of Laci Peterson and her unborn child, the Senate on Thursday sent to President Bush a bill that would make it a separate crime to harm a fetus during the commission of a violent federal crime against a pregnant woman.

Bush has pledged to sign the “Unborn Victims of Violence Act.” The 61-38 Senate vote to approve the bill, following House passage last month, came after a debate dominated by the abortion issue. Abortion rights advocates view the bill as a disguised effort to overturn a woman’s right to an abortion, saying it treats the fetus as a legal entity separate from the pregnant mother.

The bill’s supporters, including both Kansas Sens. Sam Brownback and Pat Roberts, contended that it was an anti-crime measure. “This bill is about simple justice,” said Sen. Mike DeWine, R-Ohio, the bill’s chief sponsor.

Earlier efforts to pass the bill had stalled, but it gained new momentum after national attention focused on the case of Laci Peterson, who was eight months pregnant in 2002 when she disappeared from her home in Modesto, Calif. Last April, Peterson’s remains and those of her unborn son, already named Conner, washed ashore in San Francisco Bay.

The bill became known as “Laci and Conner’s Law.”

“The best way to explain this bill is through a real-life incident that most Americans relate to,” said Sen. Lindsey Graham, R-S.C., joined earlier this week on Capitol Hill by Laci Peterson’s mother, Sharon Rocha, in pushing for the bill’s passage.

Bush, as he seeks to shore up his support from social conservatives, is expected to highlight the measure, along with his signing last year of a measure banning a procedure critics call “partial birth” abortion.

Sen. John Kerry of Massachusetts, the presumptive Democratic presidential nominee, interrupted his campaign to return to the Senate to vote in favor of an alternative measure favored by abortion rights advocates.

The alternative, introduced by Sen. Dianne Feinstein, D-Calif., would have allowed prosecutors to “double charge” a defendant for a crime against a woman that ends a pregnancy without addressing the hot-button issue of when life begins inside the womb.

But the measure was defeated in the Republican-controlled chamber, 50-49, on a largely party line vote.

When “Laci and Conner’s Law” came up for a final vote, Kerry was among 35 Democrats, two Republicans and one independent who opposed it. Voting for the measure were 48 Republicans and 13 Democrats.

Laci’s husband, Scott, has been charged with killing her and their unborn child. He has pleaded not guilty.

The federal legislation would make it a separate crime to injure or kill a fetus — “at any stage of development” — during the commission of 68 federal crimes, such as kidnapping across state lines, drug-related drive-by shootings, interstate stalking and assaults on federal property.

Feinstein, though calling for stiff punishment for criminals who assault pregnant women, argued that the Senate-approved measure could undermine a woman’s right to choose because it would have the “effect of defining life as beginning at conception.”

Kate Michelman, president of NARAL Pro-Choice America, assailed the Senate majority for putting the “far-right agenda first.”

“Instead of passing a consensus bill to punish criminals for their horrific acts,” Michelman said, the president’s allies are “taking advantage of this issue to further their campaign to oppose a woman’s right to choose.”