(CNN)

So far, we've seen Donald Trump be gracious on election night once. That was the night of Feb. 1, after Trump unexpectedly lost Iowa to Ted Cruz. No one knew how Trump would react, and Trump came out and presented a new Donald. Calm, brief, gracious. Then, within a day or two, he started accusing Cruz of having stolen the election, setting up his long-standing critique of Cruz as "Lyin' Ted."

After he lost Wisconsin on Tuesday night, it was the non-gracious Trump that appeared, in the form of a statement about how Cruz won the state.

There's a lot of bitterness and anger in there -- no doubt in part the product of having to still be slogging through random states in an increasingly desperate push to get to the 1,237 delegates he needs to clinch the nomination. That's got to be annoying to a guy who doesn't even have to show up in the studio to be interviewed on TV.

Hence the rant. But let's focus in on the assertion that floats in the middle of that muddy mess. "Not only was [Cruz] propelled by the anti-Trump Super PAC's spending countless millions of dollars on false advertising against Mr. Trump," it reads, "but [Cruz] was coordinating with his own Super PAC's (which is illegal) who totally control him."

Such coordination would indeed be illegal. And in a normal year, such a charge levied by one candidate against another would be stunning. In the year of Trump, as our Cal Borchers noted, it isn't.

It's important to explore this, so let's.

First of all, we should define what we mean. Campaign finance law prohibits candidates from working with outside groups on strategy. The reason for this is simple: Since candidates have limits on how much money they can raise and where they can raise it and super PACs don't, there has to be a wall between the two or a candidate could simply tell the PAC where to run ads and so on. In practice, that wall can be awfully porous while still not violating the law. But that's the idea. A candidate who violates the law and strategizes with a PAC is said to be coordinating with it. That's Trump's charge.

To this close observer of the Republican nominating contest, it's not entirely clear where the alleged coordination took place. A few weeks ago, Trump seized upon a ridiculous Twitter rumor to claim that Cruz's campaign manager signed off on the now-famous ad from a super PAC featuring a nude photo of Melania Trump. There's no evidence that this is true in any way, mind you, but Trump still said it in a television interview. (We reached out to the Trump campaign to see what evidence might exist and didn't hear back.)

The Houston Chronicle suggested that the claim may stem from events hosted by a pro-Cruz super PAC, Keep the Promise, that Cruz attended. As The Post reported Monday, such appearances are in that murky zone bordering coordination -- but are generally understood not to cross the line. (Candidates, for example, are expressly allowed to attend PAC fundraisers, under certain conditions.) Cruz's campaign insisted that its attorneys had approved the candidate's appearances, which obviously makes sense.

Regardless, Trump's campaign lashed out at the relationship. "This is financial corruption of the highest order, and further proof that Lyin’ Ted Cruz is totally owned by donors and special interests," the campaign said in a statement to The Post. There's a difference between corruption and illegal coordination, of course, so Trump's election-night statement makes a much bolder claim than his campaign's response to the shared-events story.

Reached by phone, Kellyanne Conway, president of one of the super PACs backing Cruz, dismissed Trump's claim.

"It's very disappointing and patently false," Conway said. "It's one thing to hurl personal insults about people's wives. It's quite another to accuse professionals and Ted Cruz himself of committing a felony by violating federal law." ("One wonders how different the political climate would be if consultants and pundits were put under oath before making comments," she added.)

We will also note that Trump himself appeared at fundraising events for a super PAC supporting him last year, before the super PAC was shuttered following a Post story that raised questions about how the campaign and the PAC were interacting. In that case, the two organizations shared a vendor, and that vendor reached out to raise money for the PAC using information he apparently received from Trump's office.

All of this falls into that same murky space between campaign and outside group. The Federal Election Commission -- currently hobbled by a 3-3 partisan split among its commissioners -- isn't taking much action to clarify what is and isn't allowable behavior. The evidence at hand, though, suggests that claiming Cruz's campaign violated the law is without merit.

Normally, candidates would be timid about leveling serious charges against one another without certainty about the veracity of the claim. That's not Donald Trump's style. And after repeated attempts by the media and his opponents to hold him accountable for throwing such things out, it's clear why he thinks he can get away with it.