Republican voters are coalescing behind [Donald] Trump, but many Republican elected officials still say they can't support him.

Well, it's possible that the new infusion of ad money against Donald Trump kept his margins in Kentucky and Louisiana down a bit. But we're also seeing something that we've never seen in 100 years, which is we are seeing the crackup of a major American political party.

If [Donald] Trump wins narrowly, Democrats can blame the loss on FBI director James Comey, who inserted himself late in the campaign in an unprecedented way.

[Donald Trump ] would make history in so many ways because he is a candidate who eschewed the traditional arts of political campaigns, including field organization, traditional advertising, debate preparation and policy knowledge.

The lesson is that voters in both parties are in a very anti-establishment, populist mood. Hillary Clinton is the establishment candidate.

As one conservative intellectual said to me - he said if the choice is between [Joseph] Stalin and [Adolf] Hitler, I'd pick Stalin, meaning Ted Cruz because he's more predictable. So there's real civil war inside the Republican 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.