What does it take to stop this guy?

That has got to be the lament within the wreckage of the Republican establishment after Donald Trump won Michigan, Mississippi and Hawaii after enduring nearly two weeks of political carpet-bombing.

There was criticism by everyone from Romney to Ryan, harsh rhetoric from his rivals and Super PAC attack ads, along with comparisons to Nixon and David Duke from the #NeverTrump wing of the media. And yet Trump still rolled to victory in three of the four states voting Tuesday.

Ted Cruz managed to win the Idaho caucuses, Marco Rubio had another terrible night as he ponders a last stand in Florida, and John Kasich had a respectable finish in Michigan that he hopes to parlay into a win in Ohio. 

But politicians winning their home states is a pittance compared to what Trump, against all odds, is managing to pull off. To carry his first industrial Midwest state, while also winning easily in a Deep South state, shows the breadth of his appeal.

The media chatter heading into Tuesday was all about whether Trump had peaked. The attacks were changing the tone of the campaign, the national polls were tightening, and he lost two out of four states to Cruz over the weekend (both caucus states, where the senator’s superior organization gives him an edge).

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More pundits started writing about how Trump would fall short of the required 1,237 delegates and how the party could snatch away the nomination in Cleveland.

So why did Trump do so well?

As he noted at his news conference, advertising has never mattered less than in this campaign cycle. Jeb Bush’s PAC spent $100 million and he went nowhere. People are tired of negative ads, viewing them as politics as usual. (Trump airs them as well, but doesn’t spend much of his fortune doing so.)

Trump’s critics believe that if there could just be more exposes, more digging, more focus on his past liberal views or current shifting of positions, his candidacy would collapse of its own weight.

But Trump’s appeal is not tied to policy specifics. It’s the image of strength he projects, the force of his personality and the notion that his business success shows he can shake up Washington.

Of course he benefits from enormous media attention, but look at how he does it. The three cable news networks carried his 45-minute presser, blowing off Hillary’s speech, because it was anything but a canned political address. He took reporters’ questions, parried criticism of his companies, talked up his vodka and steaks—it was a show. And yesterday he did a round of morning shows, taking still more questions and getting into a tiff with George Stephanopoulos over why the ABC anchor focused on the negative by bringing up late deciders who seemed to break against him. 

Maybe there is some kryptonite that can weaken this guy. But as he runs roughshod over the Republican Party, no one has been able to find it.

Howard Kurtz is a Fox News analyst and the host of "MediaBuzz" (Sundays 11 a.m. and 5 p.m. ET). He is the author of five books and is based in Washington. Follow him at @HowardKurtz. Click here for more information on Howard Kurtz.