[Mike] Bloomberg aides says he's more likely to run if it's [Donald]Trump or [Ted] Cruz versus Sanders, then there would, presumably, be space in the middle for him. But he's less likely to go if Hillary Clinton is the nominee.

If [Hillary] Clinton wins, history will also be made: She would be the first female U.S. president, of course, but also the only candidate in the modern era, other than George H.W. Bush, who managed to follow a two-term president of her own party.

Romney still enjoys the Republicans' traditional advantage among voters who are veterans, but the Obama campaign is confident it can chip away at that.

Michael Rubio said Trump's plan was impulsive and not well thought out. The other thing that's really annoying Republicans is that this was supposed to be their great week. The president gave a speech on terrorism that was not well received. They were working hard to tie Hillary Clinton to the president. Then along comes Donald Trump, and the story changes dramatically.

In 2012, Hispanics were 10 percent of the electorate, underperforming their share of the voting-age population. Mitt Romney got 21 percent of their vote, and [Donald] Trump has been polling much lower than that.

Meanwhile, there are some traditional battleground states - like Ohio and Iowa - that are becoming older, whiter and less educated. That's turning them from true battlegrounds into more reliable red states.

[Hillary] Clinton has also struggled with key groups of voters.