WASHINGTON - Senate Republicans defeated Tuesday an effort to block the Bush administration from making new battlefield mini-nuclear weapons and resuming underground nuclear tests. The largely party-line vote, 53-41, killed a measure sponsored by Democratic Sens. Edward Kennedy of Massachusetts and Dianne Feinstein of California. It was similar to legislation that the Republican-led House of Representatives endorsed in June despite White House objections. The Bush administration worries that conventional warheads won't destroy deeply buried chemical, biological or nuclear arsenals. It wants to develop nuclear warheads that could destroy enemy bunkers and "mini-nukes" that could be used by U.S. troops on...