Donald Trump

In this May 26, 2016, file photo, Republican presidential candidate Donald Trump speaks at a campaign rally at the Rimrock Auto Arena, in Billings, Mont.

(AP Photo/Brennan Linsley)

So U.S. House Speaker Paul Ryan thinks Donald Trump's comments about the Mexican heritage of a federal judge hearing a civil case against him are an example of "textbook racism," but he won't rescind his endorsement of the presumptive Republican presidential nominee?

And U.S. Rep. Bill Flores, R-Texas, says he'll vote for Trump "but in terms of getting my endorsement, I don't endorse people that bash a judge based on his ethnic heritage."

What?

Sorry, Republicans.

As the old saying goes, you can't be kind of pregnant. By backing Trump, you're giving your explicit (and implicit) endorsement to whatever nonsense comes tumbling out of his candyflake orange head.

And no amount of rhetorical contortions will get you out of that one.

You can't say you didn't know what you were getting when he scurrilously suggested that all undocumented immigrants were rapists and murderers; when he suggested that the odious "Operation Wetback" might be a good model for deporting 11 million people; or when he proposed an unenforceable and fanciful ban on foreign Muslims.

Yes, the nativist twaddle Trump spouted worked to your advantage when he was deploying it against President Barack Obama or presumptive Democratic nominee Hillary Clinton, herself a candidate who is, in many ways, as flawed as Trump himself -- as a pair of just awful headlines related to her email scandal drove home on Friday.

But whatever angles of attack open to Republicans on Clinton - and there are plenty - fall to the wayside as the national party (filling the space that should be occupied by Trump's campaign, but is not because of its well-documented barebones nature) does damage control.

So why are senior Republicans infantilizing Trump by holding onto the vain hope that he'll somehow mature and grow into a proper presidential candidate?

Take Senate Majority Leader Mitch McConnell, R-Ky., for instance.

"Using a prepared text last night and not attacking any other Americans was a good start," McConnell said, according to The Washington Post. "I think it's still time for him to act like a presidential candidate should be acting. So I haven't given up hope."

On what available evidence does McConnell base that hope?

Trump is cruising 70 years old. Presumably, any growing he had to do has already taken place. And if it hasn't happened yet, it's not going to happen at all.

And if you're rejoicing that he got through one whole speech without managing to insult a religious, racial or ethnic group, then you've set the bar so low that it's essentially meaningless.

Because, liberated from his teleprompter, Trump took to Twitter on Thursday like a 12-year-old on a sugar high, slamming Obama's endorsement of "Crooked Hillary."

"He wants four more years of Obama--but nobody else does!" Trump said of the presidential endorsement.

Clinton, or more likely, someone who manages her Twitter account, shot back "Delete your account," which was just as adult.

That prompted Republican National Committee Chairman Reince Priebus to chime in that "@HillaryClinton, if anyone knows how to use a delete key, it's you."

And there, in a moment, Priebus completed his transition from major national party leader to Chester, the annoying and yippity pup who slavishly worshipped at the feet of Spike the Bulldog in the old Warner Brothers cartoons.

As columnist Michael Gerson observed this week, Republicans are between a rock and a hard place.

On one hand, they can't very well turn their backs on the man who won the majority of the votes from Republican primary voters.

On the other, they're spending all their available free time (and political capital) putting out the Trumpian brush fires that erupt among key constituencies -- such as Hispanics - every time their presumptive nominee gets too close to an open microphone or a cell phone equipped with any sort of social media application.

Senior Republicans such as Ryan and McConnell are particularly boxed in.

As leaders they have to make difficult choices. And their desire to defeat Clinton, quite logically, is paramount.

But think, for a moment, what a strong message it would have sent if someone in a position of leadership had sent a strong message that both Trump and his divisive rhetoric - were equally unacceptable.

Some Republicans, notably U.S. Sens. Lindsey Graham of South Carolina and Ben Sasse of Nebraska, as well as U.S. Rep. Charlie Dent, of Pennsylvania, have remembered that both principle and the long-term future of the party are more important than short-term political gains.

But they are in the profound minority of their party as more Republicans jump aboard the Trump train.

Republicans, with justifiable pride, cling to their mantle as "the Party of Lincoln," and, for many years, that legacy stood in marked contrast to the Democrats of the segregationist south.

As fringe elements have risen to prominence, particularly since the emergence of the Tea Party movement in 2010, those days seem to be increasingly in the rearview mirror.

And Trump is putting ever more distance between them.

At the dawning of the American war in Iraq, another great Republican, Colin Powell, famously observed that if the United States broke Iraq, it would own the damage.

Powell's maxim was famously, if incorrectly, referred to as "The Pottery Barn Rule."

Republicans own Trump now. And they own whatever damage he'll wreak on both their party and the nation if he wins in November.