Texas Gov. George W. Bush (R), the leading GOP presidential hopeful, is staking positions on controversial environmental issues in his home state. The Texas House is considering a bill that would allow old industrial plants that have been exempted from Clean Air Act regulations to ease into compliance voluntarily. Bush supports the bill, while enviros want the plants to be forced to comply. The Texas Senate is considering a measure that would let private companies run low-level nuclear waste dumps in western Texas, accepting waste from around the country. Bush yesterday expressed concern about the bill, but did not say he would veto it. Bush has received campaign contributions from owners of old industrial plants as well as companies pushing the nuke waste bill.