President Bush late Wednesday vetoed a stem cell research bill. It is the second year in a row he has nixed legislation that would allow researchers access to more stem cell lines.

Democrats said they would continue to introduce similar legislation. This week Senate Democrats could attach embryonic stem cell legislation to an appropriations bill for the Labor and Health and Human Services departments.

Even as he vetoed the measure Bush tried to appease his opponents. He signed an executive order urging scientists to practice “ethically responsible” research.