A bipartisan group of Senators — led by Dianne Feinstein (D-Calif.), Orrin Hatch (R-Utah), Edward Kennedy (D-Mass.) and Arlen Specter (R-Pa.) — has rallied 54 colleagues to sign a letter asking President Bush to expand scientists’ ability to conduct embryonic stem-cell research.

In a letter dated June 4, 58 Senators — 43 Democrats, 14 Republicans and Jim Jeffords (I-Vt.) — called on Bush to make federal funding available for a broader array of stem-cell research projects.

Currently, only scientists working on stem-cell lines produced prior to Aug. 9, 2001, can receive federal funding for their research.

But the letter’s signatories argue that the 19 embryonic stem-cell lines that meet the federal funding requirements are contaminated, “making their therapeutic use for humans uncertain.”

As advances in cloning techniques have improved in recent years, the issue of stem-cell research has become divisive.

Proponents say that such research has the potential to cure diseases such as Alzheimer’s, Parkinson’s, cancer, diabetes, multiple sclerosis and spinal cord injuries, among others.

But anti-abortion groups oppose all forms of embryonic stem-cell research because they say it is unethical to experiment on and destroy a human life even if it is only made up of a few cells. In fact, they equate the destruction of embryos with abortion and murder.

Though the Senators’ letter was sent before former President Ronald Reagan died last weekend, stem-cell research backers are hoping to gain momentum from the media’s focus on Reagan’s decade-long battle with Alzheimer’s — a disease that has no cure and which causes a slow deterioration of the brain’s cognitive abilities.

“This issue is especially poignant given President Reagan’s passing,” said Feinstein in a Monday statement. “Embryonic stem cell research might hold the key to a cure for Alzheimer’s and other terrible diseases.”

Adding to the pressure on the White House, former first lady Nancy Reagan called on Bush last month to open more stem-cell lines to federal funding.

Indicating a willingness to legislate, the Senators noted in their letter that they “would very much like to work with you to modify the current embryonic stem-cell policy so that it provides this area of research the greatest opportunity to lead to the treatments and cures for which we are all hoping.”

The letter urged Bush to allow federal funding of stem-cell research on embryos that are donated by fertility clinics.

Though only 58 Senators signed the letter — two short of the number required to break a filibuster that would likely be mounted by opponents — Feinstein spokesman Howard Gantman said he was confident supporters could round up more than 60 votes in favor of altering the stem-cell rules, which Bush decreed by executive order in 2001.

Embryonic stem-cell research involves the cloning of human cells — cells that can be taken from the umbilical cords of aborted fetuses or live babies and from unused embryos created at fertility clinics. In order to extract the potentially therapeutic stem cells, the embryo has to be destroyed.

By signing the letter, several anti-abortion Republicans — including Hatch and Thad Cochran and Trent Lott of Mississippi — bucked the position of anti-abortion advocacy groups.

“As a right-to-life Senator, I believe that a critical part of a pro-life, pro-family philosophy is helping the living,” Hatch said in a statement.

Other Republicans to sign the letter included Senate Appropriations Chairman Ted Stevens (Alaska) and Senate Armed Services Chairman John Warner (Va.).

The Senators’ letter was put together separately from a push by Hatch, Feinstein, Specter and Kennedy to stop religious conservatives in Congress from unilaterally banning human cloning.

The four Senators have proposed a bill that bans cloning for the purpose of creating a baby, but allows scientists to use cloning techniques to create embryonic stem cells that aid research projects for new medical treatments. That bill does not have 60 supporters, Gantman said.

Sen. Sam Brownback (R-Kan.) has offered a bill to ban all forms of human cloning, including using stem cells for research and therapeutic purposes. It is similar to a measure the House passed last year.

However, neither measure is likely to see any Senate floor action this year, given the split among Republicans over the issue.