Swampy-ness aside, AT&T's hiring of Michael Cohen in January 2017 to advise the company on an $85 billion acquisition of Time Warner looked like a smart strategy.

Cohen was President Trump's longtime personal lawyer, offering insight and influence for a mere $50,000 per month. And AT&T certainly could have used insight and influence.

AT&T had agreed to buy Time Warner a few months earlier, in October 2016, and immediately encountered opposition from then-candidate Donald Trump. On the day the deal was struck, Trump said at a campaign rally in Gettysburg, Pa., that he would reject it, if elected.

“As an example of the power structure I'm fighting, AT&T is buying Time Warner and thus CNN, a deal we will not approve in my administration, because it's too much concentration of power in the hands of too few,” Trump said.

If Cohen could help soften Trump's position, then his services would be well worth the expense.

In retrospect, AT&T's contract with Cohen appears to have been a complete failure. In November, 10 months after AT&T retained Cohen, the Justice Department sued to block the company's purchase of Time Warner, citing antitrust concerns.

“I've always felt that that was a deal that's not good for the country,” Trump said at the time. “I think your pricing is going to go up.”

Whatever efforts Cohen made to grease the skids did not work. Reuters reported that AT&T chief executive Randall Stephenson called the hiring of Cohen a “big mistake” in a staff memo on Friday morning.

“To be clear, everything we did was done according to the law and entirely legitimate,” Stephenson wrote in the memo. “But the fact is our past association with Cohen was a serious misjudgment.”

The only visible evidence of Trump taking a friendlier posture toward AT&T during the period when the company paid Cohen a total of $600,000 is the shout-out Trump gave AT&T in December, during a White House event marking passage of a Republican tax bill.

“This just came out,” the president said in his remarks. “Two minutes ago, they handed it to me. AT&T plans to increase U.S. capital spending [by] $1 billion and provide [a] $1,000 special bonus to more than 200,000 U.S. employees, and that’s because of what we did. So that’s pretty good. That’s pretty good.”

The bonuses, which AT&T announced right after passage of the tax bill, instantly grabbed headlines and gave Trump a favorable talking point. Could Cohen have suggested to AT&T that tax-cut bonuses would be a way to get on the president's good side? At the time, AT&T denied that the bonuses were an attempt to curry favor.

In any case, the Trump administration remains opposed to AT&T's purchase of Time Warner, and Cohen is no longer an AT&T consultant.

It is probably unreasonable to imagine that Cohen — or anyone — could have changed Trump's thinking, which appears motivated, in part, by his personal animus toward CNN. The administration's antitrust argument, in the AT&T case, seems inconsistent with Trump's endorsement of a similar deal in which Disney would acquire the entertainment assets of 21st Century Fox for $52.4 billion.

Last month, Trump tweeted that CNN President Jeff Zucker's “job is in jeopardy.” AT&T has been noncommittal about Zucker's future in a merged company, and it is not hard to guess what Trump would like to see happen.

Short of persuading AT&T to oust Zucker or sell CNN — something the Trump administration would like AT&T to do, according to the New York Times and Financial Times — Cohen may have had little chance of paving the way to regulatory approval of the Time Warner acquisition.

Still, the exposure of his apparent ineffectiveness on behalf of AT&T adds insult to the ongoing injury of his federal investigation for possible bank fraud, wire fraud and campaign finance violations.