For the past twenty years or so, Democrats have largely thrown around pejoratives towards Republican candidates like fascist, racist, xenophobe, ill-tempered, warmonger, etc. But with that said, it is actually strange to see a candidate actually be all of those things explicitly. Donald Trump is all of those things and more. He advocates committing warcrimes, building a wall around the Southern border (a bigger one than the one currently in place, I guess), requiring all Muslims to be registered by the federal government and/or expelling them, passing a huge tax cut for the wealthy, and eliminating Obamacare. In response, both Marco Rubio and Ted Cruz argue that Trump doesn't actually mean what he says, that they are the ones who will actually commit the warcrimes, etc., and that Trump has small hands. Or something.
This last part is key - they don't attack Trump for any of his proposals, because they agree with them - but rather, they argue that Trump is lying about supporting such an agenda. Given that Trump decided to enter the stage because he's a birther, and that minority voters are violently expelled from Trump's rallies, I would say that a good portion of what he says, he believes. Still, it is weird to have a candidate for President explicitly talk about his penis on a debate stage. It's also weird that both Cruz and Rubio can call Trump a con artist, but will back him if he's the nominee.
Okay, its not all that weird. For the past 8 years, the Republican Party has played up the insanity factor. From Louie Gohmert to Michelle Bachmann to Steve King, to Mike Lee, there have been a fair number of Republican officeholders who have espoused crazed conspiracy theories. In fact, the sole reason Mitt Romney wanted Trump's endorsement in 2012 was due to Trump's support of birtherism - the belief that Obama wasn't born in the U.S. And this is a GOP that mostly believes Obama is a secret Muslim, that he was born outside of the U.S., that he is trying to tear the country apart on racial grounds (not sure how), that Obamacare is unconstitutional and evil (ironic, since its the Heritage Foundation's plan), etc. The Snopes.com page for Obama is filled with all sorts of craziness by the Right. Is it any wonder that the guy who espouses all the craziness is the frontrunner? Or that the guy in 2nd hits the frontrunner as someone who doesn't believe the craziness he espouses?
The result is pretty terrifying, since Trump has shown a willingness to exhort his crowds to violence, and he has shown a disregard for various institutions of government. If he doesn't get enough votes for the nomination, and the GOP screws him at the Convention (which is looking more and more possible), things may get uglier, fast. Let there be no mistake, 2016 is an ugly year for American politics.