The House is expected to clear a bill Thursday that would expand federal funding of embryonic stem cell research, the latest attempt to challenge White House resistance.

President Bush, who is traveling in Europe this week, has vowed to veto the measure (S 5), just as he did similar legislation last summer. An administration spokesman said June 5 that Bush will likely wait to issue his veto until after he returns June 11.

Bill supporters say they will push the issue until they cajole, persuade — or push out of office — members who vote against a veto override attempt.

In the last Congress, a House veto override effort fell 51 votes short of the required two-thirds majority of those voting. But embryonic stem cell research advocate Diana DeGette, D-Colo., said supporters are gaining ground.

“We may pick up a few votes,” she said. “Pressure really is increasing on members.”

DeGette noted that when the House passed a companion embryonic stem cell bill (HR 3) on Jan. 11, the 253-174 margin represented a pickup of 16 votes over the similar bill in the 109th Congress. Fourteen were from newly elected members who replaced opponents of such research, an issue that doesn’t split cleanly along party lines.

The Senate, which passed the current bill, 63-34, on April 11, would get the first crack at a veto override vote because the measure originated in that chamber. After accounting for absent members, supporters calculate they are one vote short of an override.

Groups backing embryonic stem cell research have ramped up pressure on Senate Republicans thought to be vulnerable in the 2008 elections — mainly New Hampshire’s John E. Sununu — to change their positions and support an override. But Sununu has called the ad campaigns against his position “misleading” and “disgraceful,” and an aide said Wednesday he remains opposed to an override.

Even if supporters garnered a two-thirds Senate majority, they stand little chance of success in the House. Its vote in January was 32 votes shy of a two-thirds majority.

Despite the odds, Democrats see the issue as a political winner. Although those opposed to such research liken it to abortion because embryos are destroyed — and say it is not only unethical but unproven — polls show strong public support. Advocates see its potential to produce treatments for numerous disabling conditions, and some states have passed laws to spur embryonic stem cell research.

“I think we should get this to the president’s desk as soon as possible so he can become even more unpopular,” Dennis Cardoza, D-Calif., said during a House Rules Committee markup Wednesday to determine the structure of floor debate.

The panel approved a closed rule, which bars amendments. Republicans wanted to be allowed to offer an amendment that would ban human cloning, defined as cloning a human embryo for research or reproduction, but Democrats rejected that request.

An anti-cloning bill (HR 2560) was defeated, 204-213, in the House on Wednesday. It would have banned cloning for reproduction but not for research.

Although Republicans are expected to offer a motion to recommit — a tool they have successfully used multiple times in the 110th to change or stall legislation — Democratic aides say supporters are confident they will be able to defeat such a motion.

“We’ll begin to bring this up over and over again until it passes,” DeGette said. “This is the beginning of a continual effort to turn this into law.”