As shown by pollster.com's "poll of polls", Obama is keeping (but not increasing) his modest lead over John McCain. What is interesting is that Obama is clearly doing a better job exciting his bases than McCain. As the graph below shows, however, Obama still has a sizable percentage of Democrats who have strongly negative views about him. This, of course, is the expected result of the primary battle:
Nate Silver explains:
A greater number of Democrats' -- about 8 percent -- have a very unfavorable view of Obama. These 8 percent are your PUMAs -- people that will probably not vote for Obama under any circumstances. Only 4 percent of Republicans feel that way about John McCain.
Obama would be thrilled, of course, if he could actually get his defection rate down to 8 percent: John Kerry lost 11 percent of Democrats to George W. Bush; Al Gore lost 11 percent to Bush and 2 to Nader; Bill Clinton lost 10 percent to Bob Dole and 5 percent to Ross Perot. In reality, Obama will probably lose almost all of the "very unfavorables" and perhaps half of the "somewhat unfavorables", which would produce a defection rate of 12-13 percent (not all of those necessarily to McCain). McCain's defection rate, by that calculus, would be 9-10 percent (not all of those necessarily to Obama).
But look, by contrast, at the enthusiasm gap between the two candidates. 56 percent of Democrats have a very favorable view of Barack Obama, while just 34 percent of Republicans have a very favorable view of John McCain. The thing that's a little bit scary for McCain is that this is after a likely voter screen has been applied, and so even after you get done filtering out those Republicans around the margins who weren't planning to vote in the first place, many of the remaining ones are still doing so for McCain somewhat grudgingly.
Read it all here.
Nate's website, by the way is (along with pollster.com), a political junkie's dream. He tracks all the state by state polling and does daily electoral college projections. Here is his latest map: