If you want to hold on to office, it's probably a good idea not to rebuke firefighters or crack jokes about illegal immigration. That's what Montana Senator Conrad Burns is learning: In the wake of his recent gaffe, political analysts are downgrading his chances of winning election against Dem challenger Jon Tester. Analyst Stuart Rothenberg has just changed his assessment from a toss-up to a "leans-Democratic" race, while Larry Sabato, director of the University of Virginia Center for Politics, is describing Burns's seat as a "probable" Dem pickup. Says Sabato: "Conrad Burns just can't survive many more gaffes."