That’s not just the usual political boasting and grandstanding. Those were actual, verifiable claims which professional fact checkers investigated and found to be untrue.

For example, Trump said in the interview that “virtually every Democrat” has said that the Trump campaign did not collude with the Russians during the 2016 election, while there was “tremendous collusion” between Democrats and the Russians.

That’s not just false but “breathtakingly false,” as one fact-checker put it. Democrats have not exonerated Trump, though some have been circumspect about what we know and don’t know about Russian meddling, and there is little evidence that Democrats were colluding with Russia.

In fact, the CIA, FBI and National Security Agency found in January of 2017 that Russia aimed to discredit Hillary Clinton and help Trump’s chances in the election, so the claim doesn’t make much sense.

The interview was not an outlier, either.

A year-end review of untrue claims from FactCheck.org found Trump dominating the list with remarks on everything from his inauguration to the Russia investigation to his own tax bill. Of PolitiFact’s 483 fact checks on Trump so far, 69% were rated “mostly false,” “false” or “pants on fire,” and his claims on Russian meddling were the “Lie of the Year.” The Washington Post found 1,950 false or misleading claims made over 347 days.

It’s easy to dismiss the scale of this problem.

After all, public trust in government is near historic lows. Most Americans think politicians lie on a regular basis (though, by and large, they typically don’t), and professional fact-checkers have been around for years and not made a substantive difference in U.S. politics. Critics will point to these stories as evidence that “Donald Trump lies” and compile “lists of Trump lies,” Trump will call the media “fake news” and “dishonest” and nothing will change, right?

But there’s substantial evidence that Trump’s approach to the truth is having an effect.

A recent Quinnipiac poll showed that 62% of voters don’t think Trump is honest,while only 34% believe he is. While Republicans remain trusting, with 75% believing he’s honest, more than two-thirds of independents don’t agree and a sky-high 93% of Democrats think he’s dishonest. By comparison 52% of votersthought Trump was not honest just after the November election — a full 10-point drop over his first year.

Trump’s trustworthiness has made it harder for him to sell his policies. While the White House boasted that the Republican tax plan would give American families a tax break, a Monmouth poll showed that half of the public believed their own taxes would go up. The various “repeal and replace” bills on Obamacare also polled poorly, despite Trump’s claims about them, some of which were clearly untrue.

During the campaign, Trump’s pitch depended a lot on salesmanship. He avoided detailed plans in favor of making grand claims about how “I alone can fix it.” As the first president without a track record in politics or the military, he essentially asked voters to take his word for it. But his reputation for dishonesty is making it harder for him to do that job.

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