They had a dream. Democrats longed for Hillary Clinton to run against Donald Trump as the genetic Republican, from now until the November election, looking to make him the face and the voice of the party, no matter who the nominee turned out to be. No matter who won, Trump would be the heart and the soul and the id of the party, the only one in the world who could make the party of Clinton and Sanders seem rational.

The Republicans had a nightmare, and it turned out to be the same thing: Trump screaming, Trump shouting, Trump kicking the furniture, Trump wetting the bed. For Republicans, having Trump in the race was like finding a rabid bat in the house; the problem is trying to coax it out of the building without being bitten. The concerns were the fear of getting down to his level, of looking too petty, of feeding his always large conviction of grievance or of seeming to diss those of his followers who had real concerns.

If Republicans took him on, it might just feed the fire, and if they ignored him, it might feed it too. It had to stop sometime, but that wasn't consoling. "At some point he will say something that even his biggest fans will recognize as a damning revelation," wrote Jonah Goldberg. "The only question is whether he implodes before or after he does permanent damage to the GOP's chances." And then, just as permanent damage seemed the one and sole option, something occurred that appeared almost magical: He loaded his gun, fired at "the Establishment" and the blowback blew off his own head.

RELATED: Mainstream Scream: Chuck Todd suggests GOP mistake embracing Trump

Trump said John McCain, with whom he was feuding, was not a war hero. "He was a war hero because he was captured … I like people who weren't captured myself." Or, as the Washington Post would define it, "McCain was shot down over North Vietnam in 1967 and suffered a broken leg and two broken arms … he was taken prisoner and received little medical treatment, instead enduring almost daily beatings and interrogations … He lost 50 pounds in 5 ½ years of captivity, and spent much of it in solitary confinement in a windowless room." (McCain was offered, and refused, early release as the son of an admiral. Trump meanwhile had five deferments during the Vietnamese war.)

Memo to Trump: Do not, as a rich, pampered jerk, take on a war hero, at least not before a Republican audience. Point number two: Do not pick a fight that links your opponents against you, and lets them attack you from high, solid ground. The rest of the field is now free to attack you, except for Ted Cruz, a coward as always, hoping to scavenge your erstwhile supporters as they drop off. With friends such as these, you do not need enemies, and Cruz is the friend you deserve.

All in all, a really good day for the Republican Party, which confined a disease before it reached outbreak as it was beginning to spread. It has redefined him as a fringe candidate instead of a leader. The danger was never that Trump was going to win, but that he could and would force the race to revolve around him, framing the issues and forcing the others to seek his support.

RELATED: John McCain: Trump owes veterans an apology, not me

On July 16, the Post said the Democrats planned to "exploit the contrast … between Trump and Clinton," and were thrilled at the thought. Now that Republicans are exploiting the contrast between Trump and themselves, that danger is over. At last.

Noemie Emery, a Washington Examiner columnist, is a contributing editor to The Weekly Standard and author of "Great Expectations: The Troubled Lives of Political Families."