Roy Moore’s insurgent win in Tuesday’s Alabama runoff for U.S. Senate has shaken the Republican establishment, which invested heavily in incumbent Sen. Luther Strange.

The Beltway GOP feared that a win for Moore would mean that Breitbart News executive chairman Steve Bannon could make good on his threats to support primary challenges to incumbents who had been insufficiently supportive of President Donald Trump’s agenda. As if on cue, Sen. Bob Corker (R-TN) announced his retirement — hours before polls closed in Alabama.

The 2018 midterm elections are suddenly more exciting for the Republican base — and much more expensive for, the Republican donor class. The conventional wisdom is that a bruising primary race makes winning the general election against the Democrats more difficult. But in a year where there are only eight Republican Senate seats up for re-election, and redistricting has helped protect the House, primary races are unlikely to hurt the overall result.

Rather, the political conditions are ripe for an insurgency. And what Bannon showed on Tuesday was that Trump’s agenda transcends elections. He and the other leading Trump supporters who came out for Moore stressed that they wanted to help the president, not to hurt him. But they have also sent Trump a signal that he dare not reverse course on the promises he made in 2016 on issues like immigration, trade, taxes, Obamacare, climate, and the border wall.

In addition, Tuesday’s result proved the enduring power and reach of Breitbart News. The website’s extraordinary performance in 2016 was no fluke. Rather, Breitbart News has built its audience and maintained its authentic brand.

And so Bannon, and Breitbart, are no longer just the most hated names inside the Beltway. Now, they are also the most feared. And that means the political movement that elected Trump in 2016 will have a louder voice than ever.

Joel B. Pollak is Senior Editor-at-Large at Breitbart News. He was named one of the “most influential” people in news media in 2016. He is the co-author of How Trump Won: The Inside Story of a Revolution, is available from Regnery. Follow him on Twitter at @joelpollak.