Chuck Todd was exasperated. Interviewing Donald Trump on Meet the Press on Sunday, Todd confronted the Republican frontrunner on his bogus claim that thousands of Muslim Americans in Jersey City gathered together to cheer as the World Trade Center fell on 9/11. Todd pointed out that the rumors of such celebrations had been investigated and were proven false, but Trump insisted that it's true because his fans have sent him tweets saying they remember it. "Well just because somebody repeats something doesn't make it true," Todd said, trying with only limited success to get a word in. "You're running for president of the United States. Your words matter. Truthfulness matters. Fact-based stuff matters."

But maybe it doesn't. It doesn't seem to matter for Donald Trump, and if a politician truly doesn't care how often he's been called out for lying, is there anything the press can do about it?

It's surely one of the press' most important tasks to police the things politicians say for veracity and point out when they lie, whether in the course of everyday reporting or in formal fact-checks. But it turns out that there's an unspoken mutual consent underlying that enterprise. The public accepts that the judgments of the fact-checkers are objective and reasonable (even if they might quibble over things like where the line is between the "False" claim and the "Pants on Fire" claim), and the politicians accept that if something they've said has been proven false, they shouldn't say it anymore.

But Donald Trump and his supporters have simply refused to offer their consent. Not only does he refuse to be held to any standard of truth, he refuses to act ashamed when he gets caught in a lie, or even grant that he might have been mistaken. And his supporters go right along — if Donald says it, it's true, and no bunch of media jerks are going to tell them otherwise.

Like so much about the Trump campaign, the candidate's lack of concern for the truth is the outgrowth of tendencies that have been present in the Republican Party for some time. For decades, conservatives have argued that the media is hopelessly biased against conservative politicians and conservative ideas. In their attempts to counter what they see as liberal bias, conservatives built an alternative media system all their own — a few newspapers and magazines, but more importantly talk radio and Fox News — that could deliver the news in a way they found more amenable. If you're part of the audience of those outlets, you hear on a daily basis that everything the mainstream media tells you is a lie, and you can only trust the conservative media.

That idea is a leitmotif running through the conservative media's discussion of every issue, foreign or domestic: The media is trying to keep the truth from you. As Rush Limbaugh once told his audience when discussing climate science, "If you know what's good for you, if you know that they're leftists, you won't believe anything they say any time, anywhere, about anything … So we have now the Four Corners of Deceit, and the two universes in which we live. The Universe of Lies, the Universe of Reality, and The Four Corners of Deceit: Government, academia, science, and media. Those institutions are now corrupt and exist by virtue of deceit."

When people who have imbibed that message thousands of times over see someone like Chuck Todd say that Donald Trump he isn't telling the truth, who are they going to believe? If they're already favorably disposed toward Trump, and he's telling them something they want to believe — in this case, that Muslim Americans are dangerous, untrustworthy terrorist-lovers — then it's easy for them to assume that the media is, just like always, hiding the truth.

So what are journalists supposed to do when confronted with someone who doesn't play by the established rules? It's a question that may not have a good answer. For reasons of professional pride, they aren't going to just stop bothering to correct a lie that gets repeated over and over. As long as Trump repeats that thousands of Muslims were celebrating 9/11 in New Jersey, they'll keep pointing out the facts (even if they don't always do it with language that's as emphatic as it ought to be). To surrender would be an acknowledgement that all the power rests with the candidate, and he can say whatever the hell he wants whether they like it or not.

But as Trump is demonstrating, the press' ability to punish a candidate for lying depends in no small part on his willingness to accept that he's wrong and take the punishment. If he refuses to do so, and finds himself rewarded by his supporters for it, then the press doesn't have many options left.