Donald John Trump is blowing it out of his backside when he proclaims his effort to stage a campaign rally in “the biggest stadium we can find.”

He intends to come to Texas to campaign for Sen. Ted Cruz’s re-election. The president said in a Twitter post that he is going to look for the largest venue in the state to stage the rally.

One quick query: How does the president expect to fill such a venue?

He has staged rallies for a couple of years since announcing his presidential campaign in June 2015. He hasn’t drawn crowds that would even begin to fill such a monumental venue.

AT&T Stadium in Arlington? Kyle Field in College Station? Memorial Stadium in Austin? Texas Motor Speedway in Fort Worth?

They’re all big venues. As in really big, man.

Does the president really believe his presence at a rally will attract 100,000 or more spectators?

C’mon!

Cruz is running against Democratic challenger Beto O’Rourke, an El Paso member of the House. O’Rourke has closed Cruz’s lead to virtually zero. The men are tied. It’s a dead heat. Yes, we have several more weeks to go before midterm Election Day.

I plan to support O’Rourke, who by my lights puts Texas’s interests ahead of his own ambition — unlike the Cruz Missile.

Cruz and Trump have exchanged some mighty angry rhetoric in the past. That’s all behind them — or so they hope.

The rally that Trump will stage? He ought to set his sights a whole lot lower than the “biggest stadium” notion. Of course, we all know that won’t happen.

If Trump has this rally in the huge venue and attracts enough supporters to fill half the seats, or fewer, he’ll still proclaim it to be the “biggest rally crowd” in the history of the world.

The Trumpkins will believe their hero, which is all that matters to the president.