The Washington Post's fact-checker said Thursday that Democrats aren't telling the truth when they say the Republican tax plan would raise taxes on most middle-class families.

In an early Thursday morning story, fact-checker Glenn Kessler gave Democrats four Pinocchios for making that claim. According to the Post, four Pinocchios are reserved for claims that are "whoppers."

"In their haste to condemn the GOP tax plan, Democrats have spread far and wide the false claim that families making less than $86,100 on average will face a hefty tax hike," he wrote. "Actually, it’s the opposite."

"Most families in that income range would get a tax cut," he added. "Any Democrat who spread this claim should delete their tweets and make clear they were in error."

Kessler noted that Senate Democrats, including Kamala Harris of California, Bob Casey of Pennsylvania, and Jeff Merkley of Oregon, tweeted that the average tax hike for families making up to $86,100 would see an average tax increase of $794.

But Kessler traced that talking point back to a report that said only 8 million of those families earning up to $86,100 — not all of them — would see an increase of that size.

"Somehow, when it got communicated down the line, that nuance was lost and it was translated into a talking point referring to all working-class families," he wrote.

Kessler noted that the data Democrats used to make their argument actually showed that taxpayers in each of the five income bands used in the analysis would see a tax cut, not a hike, and that the average cut would be $450 for 80 percent of families.

Republicans are expected to release their tax cut bill on Thursday, and are hoping to pass it by the end of the year, over objections from most Democrats.