President Donald Trump in the Cabinet Room of the White House in Washington in mid-May. (Doug Mills/The New York Times)

Donald Trump is acting guilty again.

On Sunday, the president tweeted a demand that the Justice Department investigate "whether or not the FBI/DOJ infiltrated or surveilled the Trump Campaign for Political Purposes — and if any such demands or requests were made by people within the Obama Administration!"

Two things are pretty certain: Trump is again in the fever swamp of conspiracy theory, and he's trying anything — anything — to derail or at least distract from the special counsel's probe into Russia's 2016 election meddling and any possible Trump campaign collusion with it.

The president's demands came on the heels of a revelation that an FBI source made contact with three Trump campaign associates before the election. That source's contact was part of the FBI's initial investigation into Russian meddling.

Trump has called that FBI source a "spy" who was "implanted, for political purposes, into my campaign for president."

But think about that for minute. Our intelligence services had long before learned that Russians were tinkering at the edges of our election and in other elections around the world. The FBI already had long been suspicious that Russia was looking to turn "useful idiot" characters like Carter Page to their own ends. Would we not expect and want our FBI to be protecting the candidate Donald Trump — in fact, any or all of our candidates for public office — from possible Russian influence?

But Trump is acting guilty. Trump is immediately assuming the FBI was out to catch him, thus he wants to twist the real purpose of the information gathering to make the FBI — not the campaign or even the Russians — into the culprit.

According to The Washington Post, the informant was not embedded or implanted or otherwise inserted into the Trump campaign at all. Rather, he was asked to contact several campaign figures whose names had already come up in the FBI's counterintelligence probe.

As Post columnist Eugene Robinson writes: "It would have been an appalling dereliction of duty not to take a look at Trump advisers with Russia ties, such as Carter Page and George Papadopoulos, when the outlines of a Russian campaign to influence the election were emerging."

We would expect the same if those men or others with similar ties were working for Jeb Bush, or Hillary Clinton, or Barack Obama. What's more, we'd expect those candidates to be in full support of that FBI protection. We'd expect them to be calling for the full monty to bring those Russian ties to the fore, cut them and put a stop to any future meddling. In fact, that's exactly what Clinton did when we were hearing so much day in and day out about her emails — which didn't amount to anything like this.

But not Trump. Trump is embarrassingly indifferent to the threat of foreign influence over our government. Shouldn't we wonder why? Is it because he or his campaign really did seek and happily receive foreign help to win?

Instead of demanding justice against clear foreign meddling, he and his deplorable right-wing toadies call Russia's meddling "a hoax," and the FBI's information seeker a "spy," and the special counsel's investigation "a witch hunt."

He does that because it would seem to be the last door left to him before he plays the ultimate gambit of firing those in the Department of Justice who stand between him and special counsel Robert Mueller, whom he especially wants to fire.

A Saturday night massacre didn't go so well for Richard Milhous Nixon. But Trump, clearly now in a panic as the probe homes in on his private attorney and seems to be circling his son and son-in-law, must do all he can to taint Mueller and the probe's team before he attempts to cut the legs from the investigation.

Deputy Attorney General Rod J. Rosenstein, in charge of Mueller, has responded that an existing investigation by the DOJ inspector general will now "include determining whether there was any impropriety or political motivation."

Perhaps Rosenstein is just buying time, and certainly if there was any impropriety, it should be rooted out. But the clock still ticks and the Russia meddling investigation must be allowed to run its course without political and presidential interference.

Unfortunately, bullies like Trump — and our spineless GOP Congress that uses party loyalty as an excuse for kowtowing to his outbursts — know no boundaries.

But make no mistake: It's them or our democracy.

Mid-term elections — if we are still a democracy by then — are in November.