The darkest moment of the 2012 campaign for President Obama was the first of his three debates with Mitt Romney, the Republican nominee. Obama was rusty and under-prepared, which contributed to his poor showing that night, but a big reason he lost the plot so badly is that the Mitt Romney he had prepared to debate was a composite of public statements, briefing papers, and other documentation from the past. The Romney who showed up was a shapeshifter adapting to his immediate circumstances.

So when Obama attacked Romney, accurately, for proposing to cut taxes on the affluent so dramatically that the middle class would have to pick up the tab, Romney simply and dishonestly denied this was the case.

Obama pointed out the discrepancy, but by that point the debate might as well have been over. Or at least it had transformed into something other than a debate. The shared premise disappeared, and the vast majority of people watching had no way of knowing who was right and who was wrong and how brazenly Romney had lied.

In the days afterward, Romney struggled badly to defend his tax plan, but by wide acclaim, he outperformed Obama that night. Romney lost the election, but Republicans apparently decided that his debate tactics were terrific, because they mimicked them repeatedly during the third primary debate Wednesday night. This presents a huge challenge to political reporters and, in a different way, to the Clinton campaign. The Republican policy agenda has been radical for a long time, and Republicans have mastered all the buzzwords meant to elide this fact. Their tax plans aren’t regressive, but engines of economic growth. They don’t plan to phase out the existing Medicare program and replace it with subsidized private insurance, but to “save Medicare for future generations.” Now, though, Republicans seem content to simply disclaim the contents of their own white papers. 

The exchange that most resembled the Romney-Obama row transpired between Marco Rubio and moderator John Harwood. 

Here’s how Harwood described Rubio’s tax plan: “The Tax Foundation, which was alluded to earlier, scored your tax plan and concluded that you give nearly twice as much of a gain in after-tax income to the top one percent as to people in the middle of the income scale." [Emphasis added] This is both 100 percent correct and generous to Rubio at the same time. The Tax Foundation—an advocate for supply side tax policy—dubiously assumed the regressiveness of Rubio’s plan would be diminished by its ability to grow the economy and increase people’s pre-tax incomes, and Harwood granted them the assumption.

Rather than defend his plan on the merits, though, Rubio simply claimed Harwood was wrong, and conservatives applauded with great fanfare.

No, that’s—you’re wrong. In fact, the largest after-tax gains is for the people at the lower end of the tax spectrum under my plan. And there’s a bunch of things my tax plan does to help them. … [Y]ou wrote a story on it, and you had to go back and correct it.

This answer contains a lie, an apples-oranges nonsequitur, and another lie. Harwood’s question wasn’t about the very poor. It was about why Rubio’s plan gave so much more back to the very rich than to the middle class. And he was right.

Rubio went on to note that, “five percent of a million is a lot more than five percent of a thousand. So yeah, someone who makes more money, numerically it’s going to be higher.”

This was either intentionally deceptive, or betrayed a basic misunderstanding of percentages. Harwood’s point was that Rubio is proposing to give the rich not just more dollars, but a larger percentage of dollars per income. Five percent for a thousand, ten percent for a million. Harwood was right again.

Undaunted conservatives have seized on this weeks-old tweet, to hoodwink as many people as they can into believing that Harwood went after Rubio with a false premise.

But the tweet actually proves Harwood right, and exposes both of Rubio's deceptions. Harwood didn’t have to correct a story. He corrected a tweet. And the corrected tweet lays out exactly what Rubio denied. The already-rich would get a disproportionately large windfall from Rubio’s tax plan, relative to middle-income people.

The night continued like this. Ben Carson denied his involvement with a nutritional supplement scam company that has been well substantiated. When a moderator pointed out that the $1.1 trillion hole in his tax plan would require cutting government by about 40 percent, he said, “that’s not true.”

At one point, a moderator apologized to Donald Trump for misquoting him, because he insisted, “I never said that,” with persuasive adamance. But he did say that. She’d quoted him correctly, to the word.

After the candidates abused the truth for 10 hours, Republican National Committee chairman Reince Priebus attacked the moderators, and conservatives delighted in the knowledge that the base would chalk up the whole mess to media bias, damning GOP primary voters by assuming their oafishness.

In the long run, conservatives suffer more the deeper they burrow themselves into an ecosystem of convenient misinformation. But in the short run, they've figured out that denying documented reality and attacking the messenger can completely snow over the truth. That creates a big problem for journalists, who should view the attacks against Harwood and the others as an affront to the profession.

It creates a bigger problem as the primary gives way to the general election.

When Obama ran for re-election, he enjoyed a reputation for trustworthiness. He could point out that Romney was bluffing about his tax plan, and people took it seriously. The likely Democratic nominee, Hillary Clinton, enjoys no such presumption of good faith from either the public or the media. Republicans are preparing to run against her next year by disclaiming the most controversial things they propose to do to the country and calling her the liar. If Clinton becomes the Democratic nominee, and nobody figures out how to counter Romneyesque debate tactics, the problem will grow.