Democratic presidential candidate former Vice President Joe Biden speaks during a campaign event at Dartmouth College, Friday, Aug. 23, 2019, in Hanover, N.H. (AP Photo/Elise Amendola)

One would think, after the failed coup attempt that was the Russia collusion investigation, the Democrats would understand that any accusation of wrongdoing against Donald Trump personally, or against his administration generally, is going to be met with skepticism.

But they’ve clearly not learned that lesson, because they’ve rolled out the same big guns against Trump with their newest allegations — accusations that had TV pundits like Mika Brzezinski looking like the cat that ate the cream — that Trump may have offered military protection to Ukraine in exchange for that nation looking into former VP Joe Biden’s son’s business dealings.

Those guns are basically what we already know: use the media to hammer the public over the head with the idea Trump engaged in a quid pro quo with Ukraine and then let the chips fall.

Well, Trump’s not having it.

….story about me and a perfectly fine and routine conversation I had with the new President of the Ukraine. Nothing was said that was in any way wrong, but Biden’s demand, on the other hand, was a complete and total disaster. The Fake News knows this but doesn’t want to report!

— Donald J. Trump (@realDonaldTrump) September 21, 2019

The gist of the allegations, according to the Wall Street Journal, are these:

President Trump in a July phone call repeatedly pressured the president of Ukraine to investigate Joe Biden ’s son, according to people familiar with the matter, urging Volodymyr Zelensky about eight times to work with Rudy Giuliani on a probe that could hamper Mr. Trump’s potential 2020 opponent.

“He told him that he should work with [Mr. Giuliani] on Biden, and that people in Washington wanted to know” if his lawyer’s assertions that Mr. Biden acted improperly as vice president were true, one of the people said. Mr. Giuliani has suggested Mr. Biden’s pressure on Ukraine to fight corruption had to do with an investigation of a gas company for which his son was a director. A Ukrainian official this year said he had no evidence of wrongdoing by Mr. Biden or his son Hunter Biden.

Mr. Trump in the call didn’t mention a provision of U.S. aid to Ukraine, said this person, who didn’t believe Mr. Trump offered the Ukrainian president any quid pro quo for his cooperation on any investigation.

In fact, there are stories coming out that any conversations the U.S. had with Ukraine were at the behest of the State Department, and were not hidden nor improper. The Hill’s John Solomon describes those conversations this way:

The coverage suggests Giuliani reached out to new Ukrainian President Volodymyr Zelensky’s team this summer solely because he wanted to get dirt on possible Trump 2020 challenger Joe Biden and his son Hunter’s business dealings in that country.

Politics or law could have been part of Giuliani’s motive, and neither would be illegal.

But there is a missing part of the story that the American public needs in order to assess what really happened: Giuliani’s contact with Zelensky adviser and attorney Andrei Yermak this summer was encouraged and facilitated by the U.S. State Department.

Meanwhile Biden, is under the microscope for exactly what Trump suggests.

“The underlying story here involves Hunter Biden going around the world really collecting large payments from foreign governments and foreign oligarchs in the case of Ukraine,” Schweizer, the author of “Secret Empires,” said on Fox News’ “The Ingraham Angle.”

The former VP, and Democrats, may find that this newest gambit might end up backfiring. But they should be used to that by now.