Science: Six months into their rule on Capitol Hill, the Democrats have begun to make their mark on science policy. Many of their moves have underscored differences with the White House, including efforts to overturn the ban on federal funding for work on new embryonic stem lines, prominent accusations that the Bush Administration has politicized science advice, and proposals to increase and reshape funding for climate change research (see sidebar). But as far as the Administration's most prominent science initiative is concerned, the new Congress has so far been more than supportive, at least in loosening the purse strings: It is poised to top the president's generous requests for the multiagency American Competitiveness Initiative (ACI), which is aimed at sharply increasing funds for the physical sciences.