(CBS/AP) In defiance of a presidential veto threat, senators who support embryonic stem cell research are pushing for a quick vote on a bill passed by the House that would lift restrictions on such studies.

"The American people cannot afford to wait any longer for our top scientists to realize the full potential of stem cell research," said Sen. Tom Harkin of Iowa, the bill's chief Democratic sponsor.

No Senate debate has been scheduled, according to aides to Majority Leader Bill Frist, R-Tenn., who is a doctor and an abortion opponent. He has long been an ally of President Bush, who last week said he would veto the bill.

The Republican-controlled House's 238-194 vote on Tuesday stung some abortion opponents even though it fell far short of the two-thirds majority needed to override a veto. Such an action by Bush would be the first of his presidency.

The Senate bill, sponsored by Harkin and Sen. Arlen Specter, R-Pa., is identical to the approved House version. It would lift Mr. Bush's 2001 restrictions on federal funding for new embryonic stem cell research.

Proponents say federal funding for the research on days-old embryos, using a process that destroys them, would accelerate the search for treatments and perhaps cures for diseases such as Parkinson's and Alzheimer's. They say the embryos would have been discarded anyway.

"The hope is that these stem cells will eventually be used to regenerate organs like the brain, the heart or the pancreas without the risk of rejection," said Dr. Emily Senay on The Early Show.

Opponents dispute that, questioning any evidence that embryonic stem cell research will lead to cures. They say taxpayers should not be forced to finance science they see as an attack on unborn babies and Mr. Bush's "culture of life."

In response to other critics who said that there is more promise from different stem cells that are found in umbilical cord blood and adults, Senay said scientists are pushing several forms of research.

"The full potential of all avenues of research has yet to be determined," she told Early Show co-anchor Harry Smith. "Many scientists say that stem cells from cord blood and from adults hold less promise than those obtain from the embryos. That's why scientists are so vocal about wanting to go forward with embryonic stem cell research."

Mr. Bush on Tuesday called the House bill "a mistake."

"This bill would take us across a critical ethical line, creating new incentives for the ongoing destruction of emerging human life," Mr. Bush said. He appeared at the White House with families who adopted frozen embryos, known as snowflake children, reports CBS News Correspondent Thalia Assuras.

Sen. Rick Santorum, R-Pa., one of the Senate's staunchest opponents of abortion, said he was "disheartened" by the House's approval but pleased by Mr. Bush's veto threat.

"Government should encourage lifesaving research, but should focus on science that both works and is ethical," he said.

The bill's supporters said the Senate should weigh in despite the opposition.

"Let's have an up-or-down vote," Sen. Edward Kennedy, D-Mass., said in an interview.

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