By AL CROSS
Guest columnist

Mitch McConnell made history last Tuesday when he became the U.S. Senate’s longest-serving Republican leader. But the Kentuckian’s ultimate place in history is likely to be determined by how he deals with President Trump, who continues to make history of the dubious kind.

When McConnell became leader in 2006, Republican foreign policy was pretty much what it had been since World War II – for internationalism, free trade and taking on tyrants. Today, McConnell and other party leaders stand by as Trump assaults the world order, imposing bogus tariffs on our closest allies, disparaging them in language once reserved for our enemies and doubling down on his praise for brutal dictators.

McConnell, for the time being at least, has capitulated.

He wouldn’t let Tennessee Sen. Bob Corker offer an amendment to the defense-spending bill, or allow Congress a veto over tariffs that invoke national security – not a valid concern when it comes to Canada or our European allies, but the excuse Trump used.

The allies say they must retaliate with tariffs on American goods, including Kentucky bourbon, but McConnell is deferring to Trump on a central issue for the president, avoiding what could be an intraparty crackup as Republicans try to avoid losing control of the House and Senate this fall.

“I’m still hopeful we don’t end up in a full-scale trade war,” McConnell told the conservative Washington Examiner in a 29-minute interview. “The president is confident that it won’t really come to that and I’m hoping he’s right about that. I do worry about — and a lot of my members worry about — the impact on, let’s say, Kentucky bourbon, for example, or Kentucky farmers.” He added later, “The best thing is to continue to engage with the administration, make our arguments, and hope that this doesn’t continue.”

Corker’s amendment might have gotten 67 votes, enough to override a Trump veto of the spending bill, but McConnell’s chief deputy, John Cornyn of Texas, said “I don’t think this is a time to pick a fight with the president in the run-up to a midterm election.

And Cornyn said that before the latest round of primary elections. Two of which made clear that the Republican Party has become the Trump Party: Corey Stewart won the U.S. Senate nomination in Virginia and Rep. Mark Sanford lost in South Carolina.

Stewart, who has said Barack Obama’s birth certificate is a forgery, beat the establishment Republican candidate and “won in the wealthy suburbs of Washington, full of lobbyists and defense contractors,” Benjamin Wallace-Wells wrote in The New Yorker. “The Republican establishment has not disappeared; it has accommodated itself to the Trump ethos.”

Sanford had criticized Trump, who then slammed him on Twitter, recalling the affair that nearly ended Sanford’s career. Sanford blamed Trump for his loss, saying Republicans “don’t want the tweet that I got.”

Sanford’s Republican colleague, Andy Barr of Kentucky’s 6th District, may have gotten the message. His latest fundraising email, Thursday, began, “Under President Trump and Republicans in Congress, we’re experiencing incredible economic success.” Such emphasis on Trump is unusual for Barr, who faces a strong challenger in Democrat Amy McGrath.

Corker, who is retiring and has a freer tongue than almost any of his colleagues, let loose on Wednesday: “It’s becoming a cultish thing, isn’t it? And it’s not a good place for any party to end up with a cult-like situation as it relates to a president that happens to be, purportedly, of the same party. There’s no question that leadership, in general, is wary of doing anything that might upset the president. . . . Where the Republican Party has been traditionally and where it is today is quite divergent.”

But Republicans are moving closer to Trump. After months of saying that the investigation of Russian interference in the 2016 election should proceed, McConnell told the Examiner, “They ought to wrap it up. It’s gone on seemingly forever and I don’t know how much more they think they can find out, but if the IG is through, why can’t the Mueller investigation finally wrap up?”

Actually, the Justice Department’s inspector general only looked at the FBI probe of Hillary Clinton’s emails, not the Russia investigation by Special Counsel Robert Muller, contrary to a Trump boast on Friday.

Ever since Mueller was appointed, we have wondered if McConnell has a red line for the president: Firing Mueller or his bosses at Justice? Pardoning those who have evidence against him?

McConnell’s reasons for avoiding a crackup with Trump are also personal. He has low poll ratings in Kentucky, where the president remains popular with the Republican base, and Trump-friendly Gov. Matt Bevin looms as a possible primary challenger to McConnell in 2020. In such a race, one Trump tweet might finish McConnell off.

But at some point, our record-breaking senator is likely to face a career-defining question: Will he be a leader of his party, the Senate and the country, or will he be reduced to chief piano player in the cult-house of Trump?

Al Cross is director of the Institute for Rural Journalism and Community Issues and associate professor in the University of Kentucky School of Journalism and Media. His opinions are his own, not UK’s. This column originally appeared in the Courier-Journal.