Senate Republican Leader Mitch McConnell often says politicians come to Washington to do one of two things: “either to make a point or to make a difference.”

In his record-breaking 18-year run as the top Senate GOP leader, Mr. McConnell has certainly done both, but his colleagues say the Kentucky Republican will be remembered for the latter.

“He came here to make a difference. He’s done that,” Sen. Mike Rounds, South Dakota Republican, told The Washington Times. “And he still appreciates working with members who have the same philosophy that he does.”

Mr. McConnell​, who will turn 83 next month, is stepping down from leadership but is sticking around for the 119th Congress as a chair of the Senate Rules Committee and Appropriations defense subcommittee.

When the new Congress convenes Friday, Sen. John Thune of South Dakota, the current Republican whip, will take over the top leadership slot.

In a recent floor speech honoring Mr. McConnell, Mr. Thune identified three characteristics that define his long tenure in the role: his mastery of arcane Senate procedure, his “fierce commitment” to the Senate and his work in confirming judges to the courts who will “protect the rule of law.”

The judicial confirmations Mr. McConnell led — 234 total during his time as majority leader, including three Supreme Court justices — were mentioned by every Republican senator The Times interviewed for this report.

“The highlight would have to be his ability to get a lot of judges placed on the various courts that are going to interpret the law versus make new law — from the Supreme Court on down,” Sen. John Boozman, Arkansas Republican, said.

Sen. John Hoeven, North Dakota Republican, said Mr. McConnell’s judicial confirmations have had “a big, big impact” on decisions not only coming out of the Supreme Court but district and circuit courts as well.

“Sometimes people say, ‘Oh, he’s not conservative.’ He actually is conservative, and that’s a good reflection of how he’s had an impact for conservatives,” Mr. Hoeven said.

Another example he pointed to of Mr. McConnell working to advance conservative causes is the 2011 debt limit deal that the GOP leader negotiated with Vice President Joseph R. Biden. The Budget Control Act of 2011 set discretionary spending caps for a decade enforced through automatic budget sequestration.

Other senators said Mr. McConnell’s legacy goes beyond what he did to how he led.

“I could talk about any number of bills or outcomes that he gets a lot of credit for, but I think more than anything is just a track record of protecting the conference —  even at the expense of getting absolutely bludgeoned. That is a rare skill,” Sen. Thom Tillis told the Times.

“What’s really impressive about that is when he takes the hit and he’s protecting other members, whoever those other members are, are never known,” the North Carolina Republican said. “It’s all Mitch McConnell.”

Mr. Tillis admires Mr. McConnell so much that he named one of his dogs, a 20-pound cocker spaniel-poodle mix, after him. He trains dogs in his spare time and has a tradition of naming them after conservatives he likes.

“I’ve had so many dogs I ran out of conservative presidents, so he was the first non-president that I named a conservative dog after,” Mr. Tillis said of Mr. McConnell.

Mr. McConnell’s top priority was to protect the most vulnerable members running for reelection, regardless of his relationship with them, he said. He raised money for friends and foes and made decisions about which bills to bring to the floor in the majority or which to filibuster in the minority based on the collective good of the conference.

“Quite honestly, I believe if we found ourselves in a situation where the majority was hanging in the balance, and a vote would expose some people who have been the least supportive of him, he would still support them, because the majority is all that matters,” Mr. Tillis said.

Mr. Boozman also complimented Mr. McConnell for his “tenacious” ability to keep Senate Republicans together, given the conference’s diversity of views.

“He always pushes members to the front. It’s not about him,” he said. “It’s about accomplishing a task. And I think he’s tried to protect members through the years from tough votes and things like that, putting a lot of the really difficult things on his own shoulders, versus pushing it off on others.”

As Mr. McConnell himself put it: “Leading means letting folks take a walk when they need to, and rallying together when we need to.”

Mr. Rounds said Mr. McConnell plays the long game, thinking steps ahead of most lawmakers.

“While a lot of other people are playing checkers, he’s playing kind of a three-dimensional chess. He is very careful of what he says [and] when he says it,” Mr. Rounds said. “Now he can kind of open up a little bit over the next two years. He can speak his mind as opposed to being identified as speaking for the entire conference.”

Mr. McConnell has not yet said whether he will run for reelection in 2026, but he has made clear he will focus the remainder of his Senate career on boosting U.S. defense capabilities and foreign alliances.

“The arsenal of democracy must be restored,” he said in a recent floor speech. “Peace through strength must once again actually mean something other than just a slogan.”

Mr. McConnell is a foreign policy “realist” who “doesn’t want to see America be the world’s policeman,” but he also doesn’t want Chinese President Xi Jinping, Russian President Vladimir Putin or other foreign dictators to hold that role either, Sen. John Kennedy told The Times.

“Mitch’s legacy will be that he stands and stood for the principle that weakness invites the wolves,” the Louisiana Republican said.

The GOP senators interviewed for this article all agree Mr. McConnell will still have sway over the conference despite no longer serving in leadership.

“He’s going to have tremendous influence as we go forward,” Mr. Boozman said. “Everybody respects his opinion. He’s a quiet guy, and he doesn’t say a whole lot, but when he speaks, everybody listens.”

Mr. Kennedy agreed that Mr. McConnell is “a powerful voice” in the Senate.

“I don’t agree with him all the time, but I don’t know a single person in my conference that doesn’t listen when he has something to say,” he said. “McConnell doesn’t generally go off half-cocked. If he says something, he’s thought it through, and that’s why we listen.”

Mr. Kennedy, however, has told Mr. McConnell that “he was too heavy-handed” in his leadership style at times.

“He’s old school. But old school is out, and we’re going to do it a different way,” he said. “I feel like we made it very clear in our leadership elections that most of us wanted to go in a more open direction. And I think, so far, John Thune has been very transparent.”

That type of criticism doesn’t bother Mr. McConnell. He knows his views do not always align with his colleagues, and he doesn’t intend to hold back moving forward.

“I still fully intend to keep frustrating my critics in the years ahead,” Mr. McConnell said.

• Lindsey McPherson can be reached at lmcpherson@washingtontimes.com.