A month after Gov. Sarah Palin joined Senator John McCain's ticket to a burst of excitement and anticipation among Republicans, she heads into a critical debate facing challenges from conservatives about her credentials, signs that her popularity is slipping and evidence that Republicans are worried about how much help she will be for Mr. McCain in November.
Ms. Palin, the Republican vice-presidential nominee, flew to Mr. McCain's ranch in Sedona, Ariz., on Monday for three days of preparation with a team of his aides -- a sharp contrast to the less structured preparation that led up to the senator's first debate.