With a temporary détente reached this week over President Bush’s judicial nominations, the Senate is preparing for its next legislative battle: a showdown over federal funding for stem-cell research.

The House approved legislation Tuesday on a 238 to 194 vote to allow for federal funds to be used to explore whether embryonic stem cells can help cure ailments ranging from diabetes to Parkinson’s disease. The measure now moves to the Senate under a veto threat by President Bush, who has vowed to reject the legislation if it is approved by Congress.

Senate Minority Leader Harry Reid (D-Nev.) on Wednesday described Bush as “wrong politically and morally” regarding this issue and made a plea for the president to withdraw his veto threat.

“Please, Mr. President let us do this,” Reid told a group of reporters assembled in his office.

But opponents of the bill said they were making plans to try and prevent an up-or-down vote on the legislation, and these Senators would not rule out launching a filibuster to achieve that goal.

“This is a use of taxpayer money to destroy … human life,” said Sen. Sam Brownback (R-Kan.). “I will … use all the tools at my availability, because we shouldn’t be using taxpayer dollars to destroy human life.”

Brownback expressed concerns about the bill during a private meeting with Republican Senators Wednesday and afterwards said the reaction from his colleagues “did seem to be quite positive.”

Freshman Sen. Tom Coburn (R-Okla.) said he too would work to prevent the bill from passing in its current form. Coburn said it is possible to harvest stem cells without destroying embryos and would focus his efforts on amending the bill to promote this procedure.

“The bill that is coming out of there I will work to kill unless we modify it,” said Coburn, who is also a doctor. “I am going to work to make it what it needs to be and clean up some of the untruths. You don’t need to kill an embryo to get stem cells.”

It is unclear, though, whether opponents have the votes to sustain a filibuster. As of late Wednesday, the Senate companion bill had 32 co-sponsors including several leading Democrats and Republicans. Aides said they expected that number to grow to 34 by Thursday. Sen. Orrin Hatch (R-Utah), one of the original co-sponsors, said he was confident they had the votes to overcome a filibuster and noted the current list of sponsors is not an accurate count of supporters.

“Some people have not come on as a co-sponsor because they do not want to be up front about it,” Hatch said. “But there are a lot of people who really believe we are doing the right thing here.”

The time frame in which the Senate would consider the measure has not been determined. Senate Majority Leader Bill Frist (R-Tenn.) said he has not yet spoken to the committee chairmen who would have jurisdiction over the legislation and offered a vague timeline of “the coming weeks [or] months” for possible consideration.

“I personally look forward to the opportunity to review the science, to review the ethical considerations of using stem cells for research,” said Frist, a transplant surgeon before he was elected to the Senate.

The first line of defense for opponents lies with Frist, who could refuse to call the bill up for consideration.

“I don’t think the Majority Leader is going to bring a bill like that up,” said Sen. John Cornyn (R-Texas).

But the chamber’s rules allow individual Senators to try to amend legislation and supporters of the measure acknowledged that might be the route they have to follow.

“I am not completely sanguine that we can somehow block consideration of this on the floor,” said Senate Republican Conference Chairman Rick Santorum (Pa.).

Santorum, who has close ties to the social conservative movement, said leaders in that community understand the Senate leadership may be unable to prevent the bill from advancing. But the Pennsylvania Republican added Bush’s veto threat should provide opponents the comfort that it will not become law.

“The big vote on this issue was in the House [Tuesday] and the fact there are 50 votes more than they need to sustain the president’s veto, as far as I am concerned the bill is dead,” he said.

The House and Senate are each required to muster two-thirds of their membership to over-ride a presidential veto.

Bush spokesman Scott McClellan reiterated the president’s opposition to the legislation Wednesday during a White House briefing.

“The president’s policy is that we should not be using public dollars for the destruction of life, and that’s where he believes strongly, in that ethical line and that we should not cross that ethical line,” McClellan said.

It would be Bush’s first veto since taking office in January 2001. Rep. Mike Castle (R-Del.), a leading co-sponsor of the House bill, said he was not prepared to declare that backers would have the votes in the House to override a presidential veto. But Senate Judiciary Chairman Arlen Specter (R-Pa.) expressed confidence the two-thirds threshold would be reached in the Senate to overturn the veto.

“I think if it really comes down to a showdown, we will have enough [votes] in the United States Senate to override a veto,” Specter said.

A less controversial bill that has a chance of being approved by Congress would fund research on stem cells harvested from umbilical cords. That bill was overwhelmingly approved by the House Tuesday and Brownback said he hopes his colleagues focus their attention on that legislation.