Correction: An earlier version of this column incorrectly referred to then-Sen. Joseph I. Lieberman as representing Vermont. Lieberman represented Connecticut. This version has been corrected.

Michael T. Flynn in 2014. (Lauren Victoria Burke/Associated Press)

Well, it looks as though there might be a rebellion at the Republican national convention after all.

No, delegates are not going to rise up and deny the GOP nomination to Donald Trump in favor of some last-minute white-knight candidate. But if Trump decides to nominate a Democrat as his vice presidential nominee, convention delegates could rebel and reject Trump’s choice.

The candidate in question is retired lieutenant general Michael T. Flynn, former head of the Defense Intelligence Agency. A person familiar with Trump’s vetting process told The Post: “Trump-Flynn, I’ve heard him say that, kind of test the sound of it.”

Let’s be clear: Flynn was a terrific lieutenant general. Under his leadership, the Defense Intelligence Agency predicted that the chaos in Syria was creating conditions that could allow the Islamic State to make a comeback in Iraq. He has been critical of his President Obama’s failing strategy in the Middle East and his disastrous nuclear deal with Iran. He might be a great choice for defense secretary or secretary of state.

But vice president? Next in line for the presidency?

Retired Lt. Gen. Mike Flynn is on Republican presidential candidate Donald Trump's short list of potential vice presidential candidates. Here's what you need to know about him. (Sarah Parnass,Danielle Kunitz,Osman Malik/The Washington Post)

Flynn is a lifelong Democrat. In 2015, he told Foreign Policy magazine that “I’m not a politician, but if someone were to look it up right now, I’m a registered Democrat, and I’m okay with that.” But are Republican delegates okay with that?

Flynn is not only a Democrat but also a pro-abortion Democrat. “Women have to be able to choose,” Flynn said Sunday. “They are the ones that have to make the decision because they are the ones that are going to decide to bring up that child or not.”

That used to be Trump’s position as well. But during the course of this campaign, Trump has courted Christian leaders and evangelical voters by promising to stand with them on the right to life and to nominate conservative justices to the Supreme Court who will do the same. “I’m one of you — just remember that,” he told evangelical voters last year.

Flynn is not one of them. And while many conservatives rightly doubt that, deep down, Trump is truly one of them either, they cut a deal with him — their support in exchange for his promise to govern as a pro-life conservative. If he picks a pro-abortion running mate, Trump would violate his end of that deal before he has even been nominated.

Social issues are only the start of Flynn’s problems. While we know his position on fighting the Islamic State, his positions on other issues that the conservative grass-roots care about are a mystery. Does he support tax increases to pay for more government spending? Where does he stand on Obamacare? How about climate change, cap and trade, and clean energy subsidies? Does he support school choice and conservative education reforms, or does he stand with teachers unions like most traditional Democrats? And who did he support for president in past elections? Did he back Al Gore, John Kerry and Barack Obama, and what does that say about his political priorities?

Trump has adopted a number of traditional Democratic positions on domestic policy — from the minimum wage to entitlements, taxes and trade — so he may not care if Flynn is a traditional Democrat on these matters. But GOP delegates might.

This is not the first time a Republican nominee has flirted with the idea of choosing a Democratic running mate. In 2008, Sen. John McCain (R-Ariz.) seriously considered Sen. Joseph I. Lieberman of Connecticut, who was a Democrat for most of his life before becoming an independent. Like Flynn, Lieberman took a tough stand on Islamic radicalism. But he still held traditional Democratic positions on domestic and social policy. Conservatives rose up in opposition.

They were right to do so. The vice president’s primary job is to step into the Oval Office if something happens to the current occupant. That means if Republican delegates nominate a Democratic vice president, they could very well be nominating a Democratic president. Is that what GOP delegates in Cleveland want?

It is good that Flynn is advising Trump. He needs experienced military leaders who understand the enemy we face. But if Trump tries to put a Democrat a heartbeat away from the presidency, that will cause an irreparable break with the base — and leave Trump hobbling out of Cleveland with his party more deeply divided.

Read more from Marc Thiessen’s archive, follow him on Twitter or subscribe to his updates on Facebook.