Swing State Project has a roll call of the 37 senators who voted against the bill to ease the federal restrictions on embryonic stem cell research.
Those up for reelection are the following Republicans:
George Allen (R-VA)
Conrad Burns (R-MT)
Mike DeWine (R-OH)
John Ensign (R-NV)
John Kyl (R-AZ)
Rick Santorum (R-PA)
Jim Talent (R-MO)
Craig Thomas (R-WY)
as well as the Democratic senator from Nebraska, Ben Nelson.
Over at the New York Times, you can scroll over a map of the U.S. that provides you a state-by-state pop-up of how each delegation voted. And the Times also provides a way for you to email your senators and let them know what you think of their vote.
Pundits say that it is "unlikely" that there could be enough votes (just 3 more in the Senate) to override the veto. But if you scroll down a list of Republicans who in favor of expanding embryonic stem cell research--Orin Hatch, Bill Frist, etc.--it becomes clear that reason and compassion can cross party lines.