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If Republican voters are complacent, Donald Trump can only blame himself.

In a recent interview, former White House advisor Steve Bannon expressed worry that Republican voters were too confident about the GOP keeping control of Congress, which might prevent them from being sufficiently motivated to vote in the upcoming midterm elections. Bannon has good reason for concern.

Polling strongly suggests Demcorats have a real chance at retaking the House of Representatives. Yet as Bloomberg reports, a private poll conducted by the Republican National Committee reveals that, “fully half of self-identified Republicans don’t believe Democrats are likely to win back the House. And within that group, 57 percent of people who describe themselves as strong Trump supporters don’t believe Democrats have a chance (37 percent believe they do).”

These “strong Trump supporters” probably believe this because they have been listening to the president himself. In speeches and on Twitter, Trump has constantly pooh-poohed the idea of a “blue wave” of Democrats winning and insisted offered up a counter-narrative of a “red wave” of Republican victories.

The compulsive boasting now may be backfiring.

As Trump tweeted on August 5:

The RNC report cited by Bloomberg argues that the GOP needs to put out the exact opposite message: “We need to make real the threat that Democrats have a good shot of winning control of Congress.” This will be a hard sell since admitting the possibility of defeat goes against Trump’s entire public persona.