Donald Trump’s not going to be the Republican presidential nominee.

You can feel it.

His shtick has finally gotten old.

This should have happened long ago, but it took his skipping the final pre-Iowa debate for many to realize that Trump really isn’t that interesting after all — or necessary when it comes right down to it.

He wasn’t missed. In fact, the debate was better without him.

You don’t see CNN cutting live to Trump rallies all the time. Doing so would be passé at this point. The tabloids no longer pounce on every insult Trump throws out. Either do news consumers. We’re busy. We’ve got lives to live. We get the idea, Donald.

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Regular people are debating again who the nominee will be. A month ago, it was all Trump. It was, “Oh, my God; Trump’s actually going to win.” If my ears serve me right, the conversation now is, “Trump, Cruz or Rubio?”

Trump is by no means out of the discussion — he still should win New Hampshire — but the mania is over. The snapshot of inevitability has faded, just as the winnowing of the Republican field begins in earnest. A path for others suddenly looks clear.

Trump has done an extraordinary thing for the Republican field, though. I’m not talking about attracting viewers to the debates, which he undeniably did. Trump’s real favor to the Republican Party was in making everybody but Sen. Ted Cruz look moderate, look sane really. (Cruz has too Cassius a look to ever be thought a moderate, that old “lean and hungry thing.”)

Sen. Marco Rubio, for example, who was once considered a maverick Tea Party candidate, now easily appears mainstream. I hear not particularly partisan Democrats today saying, “Rubio? Oh yes. I could vote for him.” Jeb Bush, a conservative governor who carried his older brother’s war legacy a year ago, now looks like a veritable liberal. Ditto for Gov. John Kasich, who’s the most proven fiscal conservative in the field.

Isaac Newton talked about all actions causing a reaction. I think we’re beginning to see that play out now in the Republican primary. After six months of Trump’s circus antics, people are looking for the carnival to stop. I can’t prove that empirically, but I feel it in my bones.

At the end of the day, Trump may do more to mainstream America’s conservative movement than anyone since Ronald Reagan.

He will have done it by acting like a loon.

William F. B. O’Reilly is a Republican consultant.