US President George W. Bush used his first veto to underscore his politically risky stand against federal funding for the embryonic stem cell research that most Americans support.
Some political strategists say Bush's high-profile stance on such an intensely emotional issue could hurt his Republican Party's congressional candidates in November in heartland places such as Missouri.
"This bill would support the taking of innocent human life in the hope of finding medical benefits for others," Bush said after rejecting calls that he change his policy. "It crosses a moral boundary that our decent society needs to respect."
The veto puts some Republicans in the uncomfortable position of having to chose between the wishes of their conservative backers who consider embryonic stem cells to be early human life and those in greater numbers who want to use the cells for research that could one day save lives.
"I think history will look very unkindly on this veto," said Representative Chris Shays, a moderate Connecticut Republican who helped pass the legislation.
"I believe the president is very sincere in vetoing this bill, but I think that he's been captured by his own ideology and taking his ideology to an extreme," Shays said.
"I think it will hurt" the party in November, said Representative Joe Pitts, a Republican from Pennsylvania, who supported the veto.
But he said Bush and Republicans who were allied with him were acting on moral principle and not politics.
"I'm willing to roll the dice on that," he said.