What do Vice President Kamala Harris and former President Donald Trump have in common?

They both love talking about Donald Trump.

Which is why he lost Tuesday night’s debate.

Trump had one mission for the ABC News debate: Tell voters about Harris’ long record of supporting far-left policies like defunding the police and (no joke!) taxpayer-funded sex change operations for illegal immigrants. Then reminding voters of her record at the White House helping to send inflation soaring and border security tumbling.

Instead, he repeatedly took Harris’ bait to talk about the one topic he can’t resist: himself.

It wasn’t all Trump’s fault. Republicans are right to be angry over the so-called debate “moderating” by ABC News’ David Muir and Linsey Davis. It was scandalously bad. The two media liberals attacked Trump’s statements and fact-checked his claims in ways they never challenged Harris.

And every time they dinged him, Trump talked more.

Harris did her part, too, throwing out references to things like people “leaving his rallies early out of exhaustion and boredom,” insults she knew would set him off. And they did.

“People don’t leave my rallies. We have the biggest rallies, the most incredible rallies in the history of politics. That’s because people want to take their country back,” Trump said.

When he wasn’t rambling about his rallies, Trump was talking about illegal immigrants eating America’s pets.

“In Springfield (Ill.), they’re eating the dogs. The people that came in. They’re eating the cats. They’re eating — they’re eating the pets of the people that live there,” Trump said.

Muir claimed it wasn’t true. But even if Trump had waved around a copy of “The Illegal Migrant’s Cookbook” featuring recipes for “Fido Fricassee” or “House Cat Hash,” how does this move the meter with voters?

His job was to talk to America about who Harris is — an out-of-touch, far-left politician with a failed record as vice president. Instead, Trump — who talked 10 minutes more than Harris — spent the vast majority of those extra minutes talking about Donald Trump.

He talked about the size of the crowds at his rallies. He talked about his great conversations with President Putin and Chairman Xi. He told the story of his speech on Jan. 6, and he explained how he became a “convicted felon” thanks to “weaponization.”

“They weaponized the Justice Department,” Trump complained. “And it’s never happened in this country.”

There was a lot of “Trump complaining” in the debate. What there wasn’t was a lot of was Trump “telling.”

Opinions may vary on whether Trump’s act has gotten boring. But it has certainly gotten tiring. Republican voters are tired of making excuses for a candidate who wants the most powerful job in the world, but who doesn’t have the self discipline to avoid defending the Jan. 6 rioters in order to win it.

Trump supporters claim that Harris didn’t get the same treatment as Trump, that she was able to ignore tough questions about her past support for fracking or mandatory gun buyback programs. Is this a surprise? The media treating Republicans unfairly is a phenomenon that only happens on days that end in “y.”

Trump definitely had a couple of great lines. Mocking Harris’ lack of policy specifics, he said the vice president “doesn’t have a plan. She copied Biden’s plan. And it’s like four sentences, like ‘Run Spot Run.”

At one point, Harris attempted to interrupt Trump, allowing him to fire back with one of her own favorite lines: “I’m talking now. If you don’t mind. Please.”

And then, to make sure everyone got the joke, he added: “Does that sound familiar?”

For Republicans, Trump’s performance in Tuesday’s debate is all too familiar, and it’s not a joke. At least, not a funny one. What they saw Tuesday night was one candidate who showed up ready to execute a debate strategy, and another wanted to talk about illegal immigrants eating your pets.

If there’s any good news for Trump, it’s that most debates don’t matter. They’re forgotten after a week or two as new political news moves to the front page.

The bad news is that, his performance was so lousy, the Harris campaign announced she wants to do it again.

Please don’t.

There is nothing new left to be said about Donald Trump. But that won’t prevent him from spending another 90 minutes on prime-time TV saying it, anyway.