Shock-jock radio host and former Congressman Joe Walsh has been gaining a lot of attention recently for his planned primary challenge against Donald Trump. I doubt this is because anyone seriously thinks that Walsh—with limited name recognition, no deep pockets, and no large base of support to mobilize—is going to mount a credible challenge for the Republican presidential nomination. But the announcement has been lauded as a high-profile defection by a former Trump booster.

Therein lies the problem—not so much that Walsh used to support Trump, but how he used to support him.

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