Congress passed a bill to expand stem cell research, but lawmakers are bracing for a presidential veto.

The legislation would increase the number of embryonic stem cell lines eligible for federally funded research. President Bush vetoed a similar bill last July. He is opposed to the key tenet of the bill: allowing embryos that would be discarded from in vitro fertilization clinics to be used for research.

While there may be enough votes in the Senate to override a veto, that does not appear to be the case in the House of Representatives. Expanding the use of stem cells might lead to cures for diseases such as Parkinson’s and Alzheimer’s, according to supporters.