NBC just released the results of its latest poll. Obama is opening up a big lead. More importantly, Palin is the biggest concern voters have about McCain:

NOTE FROM JOHN: Palin’s negatives have soared, but more importantly, she has now become John McCain’s greatest liability – greater than voters’ concern that McCain will be another Bush term. Normally, voters don’t care about the VP choice. In this instance they do. I think this means that the number one voter concern is John McCain’s health. Earlier today, I was watching some footage of McCain in the Republican debates in May. He was good. He looked years younger – YEARS younger. He was smart, quick, funny – he was a younger man. McCain has aged a lot in the past six months, and that’s troublesome. It shows when he talks, it shows in how he thinks and how acts/reacts to crises like the recent Wall Street meltdown. That is what, in my view, is underlying these polls. People think, people see with their own eyes, that there is a real chance that John McCain won’t make it through his presidency, and that Sarah Palin will be forced to take over. And real Americans know that Sarah Palin is not, and never will be, ready to be president of the United States of America.

From MSNBC: