Senator Mitch McConnell does not give much away even in the most private of settings.
So it was notable when the typically inscrutable Republican leader asked to speak first at an Oval Office session with President Biden and other congressional leaders called in late February to pressure Speaker Mike Johnson into putting military assistance to Ukraine up for a floor vote.
The thinking was that Mr. Johnson, the novice Republican leader whose right-wing members were threatening to oust him from the speakership if he moved ahead with the aid to Kyiv, would be more inclined to listen to a fellow Republican like Mr. McConnell than to pleas from Mr. Biden or the Democratic congressional leaders, Senator Chuck Schumer and Representative Hakeem Jeffries.
“I wasn’t trying to convince Johnson of anything other than we had a time problem,” Mr. McConnell said in an interview on Tuesday, recounting the White House meeting and his message that help for Ukraine could not wait for Mr. Johnson’s political problems to sort themselves out. “I didn’t think we had time to fool around.”
Mr. McConnell did not get immediate results. It took almost two more months and some legislative circuity. But Mr. Johnson finally acted last week and the House sent the aid package to the Senate, which followed suit on Tuesday night in overwhelmingly approving more than $60 billion in assistance for beleaguered Ukraine after months of delay and political strife.
The resounding vote delivered Mr. McConnell yet another hard-fought legislative win in a long career of bare-knuckle victories, bitter losses and partisan maneuvering. But for once it was not the Democrats he was battling.
Instead, it was powerful forces within his own party who regard America’s role in the world much differently from Mr. McConnell’s expansive view and consider him badly out of step with contemporary Republicanism and base voters.
“Obviously this was a Republican problem,” said Mr. McConnell, who suggested he was initially caught off guard by the rise of isolationism in the party of Ronald Reagan and his mantra of “peace through strength.” “For most of this time, I sort of felt like I was the only Reagan Republican left.”
It is a stark observation coming from a leader who presided over the rightward lurch of his party under former President Donald J. Trump, whose “America First” viewpoint drove the opposition in Congress to aiding Ukraine. Having bolstered Mr. Trump during his presidency, Mr. McConnell found himself having to push back on the very forces he helped to legitimize.
For Mr. McConnell, defending Ukraine against Russian aggression was a historic imperative that rose far above the standard congressional bickering, and something he regarded as a defining pursuit as he prepares to give up the leadership position he has held for nearly two decades. He was determined to see the fight through, he said, “not only for us, but for the whole democratic world.”
Members of both parties argue that the aid would have never been approved without Mr. McConnell’s unrelenting push for the money and his refusal to give up at multiple points when it looked as if there was little hope for success and conventional wisdom said the aid was a dead letter.
“He had a spine of steel and would not give into the pressure from those in our caucus who did not have the depth of understanding of the stakes and who had reached different conclusions,” said Senator Susan Collins, Republican of Maine, who accompanied Mr. McConnell on a trip to Ukraine in 2022 that he used as a backdrop to make a forceful case for the aid to skeptics in his party. “Mitch was steadfast and unwavering.”
“I give him a huge amount of credit,” Mr. Schumer said of his Republican counterpart, a man he has clashed with for years over spending, federal policy and the courts. “We were shoulder to shoulder on this.”
As he considered the past few months, Mr. McConnell said he was able to not only stem the internal tide of isolationism, but also win over some wavering Republicans. He did so in part by hammering away at his argument that Russia needed to be stopped in Ukraine and that America’s role was vital internationally. He also picked up some G.O.P. support by making the case that arming Ukraine would create jobs at home as American companies would be called upon to manufacture new weapons to make up for those being sent to Kyiv.
In the end, Mr. McConnell gained nine G.O.P. votes in support of Ukraine from an earlier showdown on the issue, delivering a total of 31 Republican votes for passing the package — well over half of his ranks.
“We’ve gained strength,” Mr. McConnell said. “I think we have successfully pushed back against the completely nonsensical arguments that have been made, in my opinion. I think we turned the corner.”
But Mr. McConnell did not convert all of his members by any means. Fifteen Republicans opposed the legislation, aligning themselves with Mr. Trump. Many of those opponents obliquely castigated Mr. McConnell for going along with Democrats in what Senator Eric Schmitt, a freshman Republican from Missouri, characterized as legislation that “is on a collision course with history and the will of the American people.”
“We are witnessing the swamp at its worst,” said Senator Tommy Tuberville, Republican of Alabama and another opponent of the legislation.
Mr. McConnell shrugged off such complaints, saying he has been willing to break from some in his party when he deemed it necessary, such as on spending issues and raising the debt limit.
“Only rarely have I benefited from a united conference,” he said. “So yeah, there are different points of view.”
Mr. McConnell did say that the split among his members over Ukraine did not contribute to his decision to step out of leadership next year.
“It didn’t have anything to do with this,” he said. “I’ve been doing this for 18 years and I was 82 years old and I thought it was time to go in a different direction.”
People close to Mr. McConnell, who had some serious health episodes last year, said his decision to give up his leadership post seemed to have taken some weight off his shoulders. And he seemed liberated by the Senate vote on Tuesday night, taking far more questions than usual at a news conference immediately afterward.
He pinned some of the blame for Republican opposition to Ukraine on the “demonization” of the country by the conservative media personality Tucker Carlson — a pointed jab he might have avoided in the past.
Mr. McConnell said he is far from done when it comes to being outspoken and promoting America’s role in the world, saying he intends to be heavily engaged on foreign policy issues, pushing for more military spending and calling out those who are wrong — even if they are fellow Republicans.
“No question about it, I’ll have more latitude,” he said about his future outside leadership in the remaining two years of his term. “When you are in this job, first of all you have to take a lot of arrows. Second, you don’t attack your members either on or off the record. And that’s the way I have operated for 18 years. So in that sense I feel free to pursue my interests.”
“I’m hoping,” he said, “people will care what I say because I used to be leader.”