Joe Scarborough: “Trump will always be Trump, and there is no need for anyone in the Republican establishment to think otherwise. The best they can do is ride this wave of dissatisfaction and learn a lesson or two from it… But anyone looking for salvation from party leaders or major money players are looking in the wrong place. The burden of dethroning the Donald falls on GOP politicians like Jeb Bush, Scott Walker and others who have politely played by the old rules of an outdated political system that is no longer relevant to most Americans.”

“The longer Trump’s opponents play it safe, the longer Trump will continue his political ascent. If anyone in the field plans on showing the type of courage that doesn’t spill out of a focus group or benchmark poll, the DC Establishment had better hope they find it soon. Because there is at least a small chance that Mr. Trump will stop making unforced errors soon. And if that happens, there is no telling where this crazy race goes next.”

“As one of the most liberal newspapers in the United States, the poll results were just too much for them to bear.”

— Donald Trump, quoted by Politico, on the blistering Des Moines Register editorial calling for him to quit the presidential race.

The Des Moines Register called on Donald Trump to end his presidential campaign.

“He has become ‘the distraction with traction’ — a feckless blowhard who can generate headlines, name recognition and polling numbers not by provoking thought, but by provoking outrage.”

“In just five weeks, he has polluted the political waters to such an extent that serious candidates who actually have the credentials to serve as president can’t get their message across to voters. In fact, some of them can’t even win a spot in one of the upcoming debates, since those slots are reserved for candidates leading in the polls.”

Ryan Lizza: “Republicans almost universally acknowledge that, over the long-term, their Party needs to increase its appeal to Latinos in order to win the White House. The first step down that path is to talk about immigrants from Latin America in a respectful way and to marginalize prominent politicians who attack immigrants.”

“However, what is good for the Party over all is not necessarily good for individual candidates.”

“One can laugh at Trump and his absurdities, but it’s wrong to say that he doesn’t matter. He has exposed and exploited the Republican Party’s two great weaknesses: the fact that many of its voters don’t agree with Party leaders on immigration and the fact that the Party is powerless to do much about it.””

“They were begging me to do the show. That’s why NBC’s angry at me. They’re angry at me because of that. So NBC’s angry at me because I ran for president.”

— Donald Trump, quoted by the New York Times, on NBC cancelling his contract to host The Apprentice.

John Sides: “Donald Trump’s surge to the front of the GOP presidential polls has occasioned not a little media attention and endless speculation as to why. You can disregard most of that speculation. The answer is simple: Trump is surging in the polls because the news media has consistently focused on him since he announced his candidacy on June 16.”

First Read: “In a normal world of politics and for a normal political candidate, this would be a tipping point: As the party abandons Trump, so would GOP primary voters. But this isn’t a normal time in American politics, and Donald Trump isn’t your normal political candidate. He’s unpredictable, and that’s the issue. He doesn’t play by conventional rules, so conventional patterns might not apply.”

Rick Klein: “The Trump portion of the 2016 race may be long remembered, though like the birther saga of the last cycle, there will be little of use to reflect upon. In any event, it’s winding down now, or so it would appear, in predictable if not quite painless fashion. What’s undoing Donald Trump’s legitimacy may seem like a typical series of rants. Yet he has shown that even he can go too far: His disparagement of John McCain opened Republican floodgates of criticism – and not because McCain himself remains particularly beloved inside the GOP. This won’t end Trump’s polling strength by itself, if his own history with controversial comments is any guide. But it is all but certain to end a ‘let Trump be Trump’ sentiment among his rivals, borne out of both fear of the Donald and a desire to attract his supporters down the line. Trump will continue to be loud and defiant, but he will cease being relevant long before votes are cast.”

“A number of my competitors for the Republican nomination have no business running for president. I do not need to be lectured by any of them.”

— Donald Trump, in a USA Today op-ed.

The New York Times looks at possible fallout from Donald Trump’s comments over the weekend about why Sen. John McCain is considered a war hero.

“It was an improvised fit of pique, roundly and vigorously denounced by his rivals all weekend, that exposed the biggest vulnerability of Mr. Trump’s campaign for president: It is built entirely around the instincts and grievances of its unpredictable candidate  — and does not rely on a conventional political operation that protects presidential hopefuls from themselves.”

“It remains to be seen whether Mr. Trump’s standing in public opinion surveys will suffer from the episode with Mr. McCain. But recent national and early-primary state polls put Mr. Trump in the top tier of candidates.  If nothing else, the weekend reaffirmed that Mr. Trump is running a presidential campaign on his own unique terms.”

Dan Balz: “Trump has benefited from being cast as a not-quite-serious presidential candidate, which has allowed him to carry on as he has.”

“No, not at all… Very importantly, I got a standing ovation, the biggest ovation they had all weekend, by far. When I left the room, it was a total standing ovation. It was wonderful to see. Nobody was insulted…. I’m very disappointed in John McCain because the vets are horribly treated in this country.”

— Donald Trump, quoted by Politico, saying he does not owe McCain an apology for saying he’s only a war hero because he was captured.

Donald Trump’s “surge in the polls has followed the classic pattern of a media-driven surge. Now it will likely follow the classic pattern of a party-backed decline,” Nate Cohn writes.

“Mr. Trump’s candidacy probably reached an inflection point on Saturday after he essentially criticized John McCain for being captured during the Vietnam War. Republican campaigns and elites quickly moved to condemn his comments — a shift that will probably mark the moment when Trump’s candidacy went from boom to bust.”

“His support will erode as the tone of coverage shifts from publicizing his anti-establishment and anti-immigration views, which have some resonance in the party, to reflecting the chorus of Republican criticism of his most outrageous comments and the more liberal elements of his record.”

Weekly Standard: “Donald Trump confirmed two things during a stop in this central Iowa town Saturday: He has no class and he may well run as an independent when he does not win the Republican nomination.”