The initials stenciled in thick block capitals, in yellow, on a dark blue background, are designed to be noticed.

F, B, I, emblazoned on caps, t-shirts and jackets, they gained icon status, slung around the shoulders of TV characters like Scully and Mulder in the X-Files,

and spawned dozens of light-hearted imitations from the uniforms of the full-blooded Italians wrestling team to less PG-13 slogans.

But as of last week, there's a new and more serious model available. Still, the initials F, B, I, yellow, out of dark blue, but above them a new motto.

Defund. The t-shirts and caps sell for $30 on the website of Congresswoman Marjorie Taylor Greene.

Within days of the F, B, I search of Donald Trump's home at Mar-a-Lago, Greene, several of her house colleagues and some leading Republican candidates for House and Senate were calling for the agency to be defunded, abolished.

Even destroyed for unjustly persecuting Donald Trump. Its language more often associated with their sworn enemies, the Progressives.

And it has an impact. Threats against law enforcement officers have surged. This week Mike Pence, Trump's former vice president, pleaded with his party to defend the thin blue line.

But Pence himself is part of a thin red line. Among Republicans, long the party of law and order, the voices speaking up for law enforcement have been drowned out.

The defining test in the GOP primaries is loyalty to one man above party, country, and rule of law.

I'm John Prado and this is Checks and Balance from the Economist.

Each week we take one big theme shaping American politics and explore it in depth.

Today, will anything break Donald Trump's hold on the Republican Party?

Despite his attempts to overturn the results of the presidential election, his friendliness with dictators, hostility to old allies, and multiple active investigations against him,

the former president remains the most powerful man on the American right.

Midterm hopefuls and former critics are vying for his approval. Decenters are being swept away.

How did Donald Trump keep control of the GOP?

And despite all obstacles, will he be the next Republican nominee for president?

With me this week to discuss Donald Trump's tightening grip on the Republican Party and the likely consequences of the FBI's visit to Mar-a-Lago

are Charlotte Howard and Idris Calune.

Idris, you've racked up an awful lot of miles this week reporting for the Economist.

But before we get into what you discovered on that reporting trip, how is the drive from Denver to Jackson?

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