Early in the Trump presidency, I theorized that he was uniquely able to bring the two parties together to pass a significant and elusive piece of legislation. I just got the issue wrong.

While I surmised that President Trump was perhaps the one person who could bring the GOP base with him and force through comprehensive immigration reform, Congress on Tuesday moved forward with a less-revolutionary idea for which Trump pulled off a similar trick. After Trump jumped on board with prison reform last month, Senate Majority Leader Mitch McConnell (R-Ky.) relented in his opposition, and other Senate Republicans joined in overwhelmingly passing the First Step Act. The bill seems a good bet for passage in the House and Trump’s signature.

The package isn’t as robust as the most ardent reformers wanted, but it’s significant. It reduces mandatory sentences. It cuts 53,000 years off existing sentences. It addresses the sentencing disparity between powder and crack cocaine. It emphasizes reducing recidivism. It got 87 votes in the Senate, which is almost unheard-of these days.

And the whole thing reinforces that central paradox of Trump’s presidency that I wrote about: Despite being the most polarizing and controversial president in modern U.S. history, Trump is in the unique position of loosening the gridlock in Washington — if he wanted to.

Basically, Trump has spent so much time and effort cultivating his own base — and that base is so utterly devoted not to his policies but his entire ethos — that he can do things other GOP presidents couldn’t. The details matter less than ever. He has turned the GOP more toward non-interventionism, trade protectionism and populism and away from Wall Street and influential fiscal conservative groups. He gave the farm away to Democrats in the 2017 debt-ceiling debate, and the Republican base barely made a peep. He has made congressional Republicans terrified of running afoul of him, because they know what kind of blowback they could get if he just inserts their name in a tweet.

All of which means, to the extent he wants to get congressional Republicans to do things that have sufficient Democratic support and can pass, he stands a better chance than anybody in recent decades.

It’s tempting to draw conclusions about what that will mean moving forward, especially now that Democrats will control the House. There is now a requirement to be bipartisan in a way there simply wasn’t before, and perhaps Trump will change his tactics.

I’m less than convinced that will happen. Even as Trump has built a reservoir of goodwill with the GOP base, such goodwill is always finite. Trump can’t expect to constantly be cutting deals with Democrats on high-profile issues and expect the GOP base to remain so loyal. He also needs to make sure his base is as enthusiastic for his 2020 reelection campaign as it has been for the past two years. Concessions on the debt ceiling and prison reform are one thing; persuading the GOP base to embrace paths to citizenship (often referred to as “amnesty” in conservative circles) is quite another.

Indeed, there’s also no question that doing prison reform was much, much easier than something like immigration would be. In this case, Trump really just needed McConnell to bring it to a vote on what has been a pretty bipartisan issue. (Though it’s worth noting that similar prison reform efforts failed in the Obama administration.) Immigration would require giving enough GOP members cover to vote for something they have been terrified for years might cost them in their primaries.

There’s also the matter of Trump’s actual issue positions. While they are perhaps malleable on many things, that’s only true to an extent. He backed out of an immigration deal last year when he was convinced it wasn’t hard-line enough. He clearly feels strongly about trade and scaling back foreign alliances. And passing bills may not even be his chief goal; he often seems more interested in shaking things up and being the center of attention than producing substantive legislation.

But it remains true that he could grease the skids if he wanted to. And in the past couple of weeks, in a low-profile and relatively safe manner, he proved it.