WASHINGTON – A stubborn Senate voted Wednesday to ease restrictions on federally funded embryonic stem cell research, ignoring President Bush’s threat of a second veto on legislation designed to lead to new medical treatments.

The 63-34 vote was shy of the margin that would be needed to enact the measure over presidential opposition, despite gains made by supporters in last fall’s elections. Maine’s Republican Sens. Olympia Snowe and Susan Collins both voted for the bill.

“Embryonic stem cell research holds considerable potential to treat and perhaps even cure a vast array of diseases and conditions,” Collins said on Tuesday. “It is estimated that more than 100 million Americans are afflicted by diseases or disabilities that have the potential to be treated through this promising research.”

“Not every day do we have the opportunity to vote to heal the sick,” said Claire McCaskill, D-Mo., a senator less than 100 days after a tough 2006 campaign in which the stem cell controversy played a particularly prominent role. “It is a noble cause,” she added.

“We’re going to use federal money, indirectly or directly, to destroy embryos,” countered Sen. Tom Coburn, R-Okla., echoing Bush’s argument against the measure. Coburn said claims of imminent scientific breakthroughs from embryonic stem cell research are unsubstantiated and that adult stem cells have been shown to be useful in a variety of cases.

The House, which passed similar legislation earlier in the year, is expected to adopt the Senate’s version in the next several weeks for Bush’s veto.