The Republican leadership of the House of Representatives has told party moderates that the House will vote this year on a proposal to modify President George W. Bush's stem cell research policy, opening another contentious moral, theological and scientific debate about when life begins and ends. Representative Michael Castle, a Republican from Delaware, who is the leader of a group of party moderates that has been pushing to ease restrictions on financing stem cell research, said his party's leadership had pledged to take up some version of a proposal to allow federally financed research on stem cells taken from leftover frozen embryos from fertility clinics.