LOUISVILLE — Pushing back against isolationism in his own ranks, Senate Republican leader Mitch McConnell said Thursday the challenge of deterring America’s adversaries should be “front and center” for the next president, as he advocated maintaining a strong military and support for allies, especially in war-torn Ukraine.

Speaking to a home-state crowd in Kentucky, McConnell evoked Ronald Reagan’s mantra of “peace through strength” as he spoke in stark terms about foreign policy risks and how the U.S. should respond.

“What is the big challenge ahead?” he said. “You could argue it’s a situation potentially more challenging than World War II. You’ve got an axis of evil — North Korea, China, Russia, Iran and Iran’s proxies — all talking to each other. What do they have in common? They’re all authoritarian regimes. They hate democracy. And they’re competing with all of the democratic countries around the world.”

The American response, he said, should include projecting a united front with allies along with a robust defense that he called the best deterrent against adversaries.

“I’m convinced we can prevent the next war by doing a better job of being prepared for it,” he said.

Those challenges should be a priority for the next occupant of the Oval Office, the senator said.

“No matter who wins the presidential race, and obviously I have a preference, … this issue needs to be front and center,” McConnell said. “And it isn’t about charity. This is not charity. This is in our own interest because the democratic world needs a leader and there’s nobody that substitutes for American leadership.”

McConnell supports Republican Donald Trump’s bid to return to the White House. His endorsement of Trump several months ago was a remarkable turnaround after having criticized him as “morally responsible” for the Jan. 6, 2021, Capitol attack.

But the two men differ on the U.S. role in the world, reflecting a fundamental struggle among Republicans over whether to follow Trump’s “America First” doctrine on foreign affairs or an internationalist view to steadfastly stand with American allies.

McConnell didn’t mention Trump or Democratic rival Kamala Harris by name while speaking at the Kentucky Farm Bureau’s country ham breakfast — a late-summer tradition that attracts leaders in politics, business and education.

In a short interview after his speech, McConnell said if Trump keeps the focus on inflation and immigration, he will win in November.

McConnell, the consummate political strategist, kept his focus on policy, especially foreign affairs, in his speech. The Kentuckian championed legislation that eventually won congressional approval to provide Ukraine with weapons and other aid as it fends off Russia’s invasion.

Pushing back against Republican opposition to the aid, he noted that most of the money is spent in the U.S. “as we retool our industrial base for the big challenges ahead and send the older weapons to Ukraine.”

“The Russians must fail, because it is a lot bigger than the border between Ukraine and Russia,” McConnell said. “These are brave people fighting for their independence against one of our biggest adversaries in the world. Why in the world would we not want to help them? This is a big problem going forward.”

Afterward, McConnell said the GOP lawmakers who backed aid to Ukraine weren’t punished by voters back home in their primary elections.

“The American people, I think, understand it’s important to support Ukraine,” he said in the interview. “And I think we’re going to continue to do that no matter who gets elected in the White House.”