The prospect of Robert F. Kennedy Jr. leading the Department of Health and Human Services was already highly controversial, but reporting from late last week took the story to a new level.

According to several leading news organizations, a lawyer named Aaron Siri has petitioned the government to revoke its approval of the polio vaccine — and Siri is reportedly working with Kennedy on choosing federal health officials for the incoming Trump administration. (Katie Miller, a spokeswoman for Kennedy, told The New York Times that Siri has been advising Kennedy but has not discussed his petitions with Trump’s pick to HHS.)

It was hard not to wonder how Senate Minority Leader Mitch McConnell, a polio survivor, would respond to the news. As it turned out, we didn’t have to wait too long to find out.

In a statement to NBC News, the Kentucky Republican — who’ll soon step down from his GOP leadership post — didn’t mention Kennedy by name, but the longtime senator said anyone seeking a confirmation vote must be specific about their intentions related to the polio vaccine.

“Anyone seeking the Senate’s consent to serve in the incoming Administration would do well to steer clear of even the appearance of association with such efforts,” McConnell wrote. He added that “efforts to undermine public confidence in proven cures are not just uninformed — they’re dangerous.”

It was a notable brushback pitch from a key GOP official, but it was also part of a recent pattern: McConnell has thrown a lot of these pitches at Trump and his team lately.

• In an interview with the Financial Times, published last week, McConnell warned about the dangers of isolationism, which he seemed to tie directly to his party’s incoming president. “We’re in a very, very dangerous world right now, reminiscent of before World War II,” the senator said, adding, “Even the slogan is the same. ‘America First’ — that was what they said in the ’30s.”
• McConnell has a newly published essay in Foreign Affairs magazine, warning against the “right-wing flirtation with isolation and decline.” Referencing a signature phrase from Trump, the Kentucky Republican added, “America will not be made great again by those who simply want to manage its decline.”
• The senator’s written piece echoed a speech he delivered earlier this month, rejecting his party’s isolationist wing.
• In Congress last month, Matt Gaetz’s bid to become the next attorney general collapsed in the face of opposition from GOP senators. While there was no official tally on the scope of the Republican opposition to the former Florida congressman, The New York Times reported that McConnell was among those staunchly opposed to his prospective nomination.

When political observers take stock on Capitol Hill, looking for Republicans who might be a thorn in the president-elect’s side, they tend to focus on members such as Alaska’s Lisa Murkowski and Maine’s Susan Collins. But what if McConnell — who’s expected to retire at the end of his term, and who doesn’t appear to have anything to lose by standing up to Trump — unexpectedly joins the faction of Trump skeptics?

To be sure, it’d be a mistake to get one’s hopes up. After all, McConnell publicly condemned Trump’s role in the Jan. 6 attack in the aftermath of the violence, only to vote with his party when it came time to consider the articles of impeachment. As my MSNBC colleague Ja’han Jones recently noted, McConnell has arguably been “among the biggest enablers of Donald Trump’s rise in the Republican Party and American politics.”

But the senator nevertheless appears increasingly willing to express discomfort with the state of the contemporary GOP.

We’ve been building up to this point for quite a while. Early on in Trump’s presidency, the Republican looked to McConnell as someone who would simply follow the White House’s demands. When the senator tried to explain how government worked, a “profane shouting match” soon followed.

After the 2020 elections, the relationship collapsed further: Trump condemned the GOP leader as a corrupt “hack,” targeted McConnell’s wife, practically begged GOP senators to replace McConnell as their leader, said McConnell “has a DEATH WISH” for disagreeing with Trump’s legislative strategies, and told The New York Times, on the record, that he considered McConnell to be “a piece of s—.”

As for McConnell, a book published by The Associated Press’ Michael Tackett last year added that McConnell described Trump behind the scenes as “stupid” and a “despicable human being.”

It might seem as if their relationship couldn’t get much worse. We’re about to find out if that’s true.