Prognosticator Nate Silver of FiveThirtyEight has long been dismissive of Donald Trump's chances to win the GOP nomination, but that's changing and fast. In fact, Silver is now talking about Trump's potential as a catalyst for a party realignment of historic proportions.

Democrats are preparing to pounce on that opportunity.

Democratic pollster Stan Greenberg has just released a major report attempting to identify the fractures within the Republican Party and what campaign themes might allow Democrats across the nation to woo moderate Republicans away from the GOP come November. "It's mind-boggling," Greenberg told Politico. "They're considered illegitimate within the Republican Party, and no one is speaking to them." The potential for a major shift is much greater if Trump is the nominee, Greenberg reports.

If Trump is indeed the winner of the GOP primaries, I expect we'll see a lot of ads like this one, released by U.S. Rep. Ann Kirkpatrick, the Democrat seeking to unseat Sen. John McCain in Arizona: