During his four years in the House, James Lankford kept looking across the Capitol at the Senate and figuring something was wrong.

Now, in the Senate himself, the Oklahoma Republican is determined to do something about it.

Mr. Lankford is pushing changes to the nominations process, he’s part of a new select committee looking at budget reforms, and he even has his eye on a bigger filibuster reform, as he seeks to fix an institution that’s slipped from the World’s Greatest Deliberative Body into thorough debilitation.

His nominations plan would speed presidential picks through without all of them having to take up to 30 hours of debate. District court nominees and appointments to less than Cabinet-level positions wouldn’t have to absorb a day and a half of time, and thanks to Democrats’ 2013 “nuclear option” maneuver can be confirmed without having to face a 60-vote check.

Mr. Lankford says he’s got enough support to get the proposal out of committee, but Democrats are reluctant — even though they supported a similar change for President Obama five years ago.

“I don’t know of any American who’s going to be ‘Hey, you know what’s running well? The Senate,’” Mr. Lankford says. “No one’s going to say that, because it has become a place that’s known for not doing its job. And the rules in place to protect debate are now being used to keep us from having debate.”

The 50-year-old senator, who sat down with The Washington Times last week, has found himself in the middle of some of the biggest issues of the day.

His overtures last year signaling a willingness to work on granting Dreamers a pathway to citizenship was seen as a key indication by activists that there was a chance to get something done on an issue that’s bedeviled Congress for 20 years.

He sponsored a plan with Sen. Thom Tillis, North Carolina Republican, to create such a pathway — but said it would have to be coupled with enforcement measures.

Activists, though, were unwilling to move toward Mr. Lankford to curtail future illegal immigration, and the Senate stalemated last month, defeating a series of plans, including what he said was a generous offer from President Trump.

“For me the issue was a lot of people that opposed the president’s proposal were people that had never read it. Because if you read it — rather than just knee-jerk, ‘the president put it out, that’s bad’ — if you actually read it, most people would look at it and go ‘that’s pretty rational to be able to actually solve the issue,’” he said.

“My assumption is they actually don’t want to stop illegal immigration, because if they did, there is a way to really do this,” he added.

Fresh from that fight, Mr. Lankford now has his eye set on a groundbreaking change that, once a filibuster has been headed off, would limit debate on lower court picks to just two hours, instead of the current 30, and limit a number of other executive-branch picks to eight hours’ debate.

He says he’s got enough support from Republicans to clear the Rules Committee, and says he’s been promised a vote in the committee after spring vacation.

Then, leadership staffers say, it’s up to Mr. Lankford to build support for a floor vote, which will require at least 60 votes’ support — in a chamber where the GOP controls just 51 seats.

In theory it shouldn’t be hard. A similar but temporary rules change passed in 2013, after negotiations by then-Democratic leader Harry Reid and GOP leader Mitch McConnell. The vote then was 86-9, and 38 of those Democrats who voted for it are still in the Senate.

But they’re less enthusiastic now that it’s Republicans, and in particular President Trump, who would benefit.

“Some would tell me ‘Sure, I would vote for this as long as it begins in January 2021,’” Mr. Lankford says of his conversations with Democrats. “There’s absolutely no way. No. 1, that’s not rational. No. 2, that’s not what we did in 2013 to say sure we’ll vote for this as long as it starts after the next president. There’s no way we would agree to that, nor should we — nor should they agree to that.”

He said he has a few Democrats who have said — privately — they will support him, but there are some Republicans who haven’t committed to back him yet. All told, seven Republicans still in the chamber voted against the 2013 Reid rules change.

“I get Democrats are mad at President Trump, but if this keeps continuing on we hit a tipping point where the gridlock that’s on Capitol Hill becomes the whole city. You don’t have deputy assistants, you don’t have everything else,” he said.

“I guarantee what they do to us, we’re going to do to them more,” he added.