Once again, Robert Mueller's team is nailing a witness it wants to use to incriminate President Trump in some nefarious scheme with a guilty plea for lying, and thereby discrediting any future testimony against the intended target.  Well, at least it gives them a scalp to nail to the wall to justify the tens of millions of dollars already expended over the last two years in an effort to unseat a sitting president.

Cohen exits N.Y. federal courthouse after guilty plea (CNN screen grab).

Trump's enemies are certain that the end is near.

To help Trump, Cohen lied to Congress about Trump’s business interests in Russia. The President’s own denials during the campaign were also false or misleading, and underscore the importance of investigating any financial entanglement between Trump and Russia.

— Adam Schiff (@RepAdamSchiff) November 29, 2018

As Brooke Singman of Fox News points out:

Significantly, Mueller's questions to Trump included a specific inquiry about any interaction or communication Trump may have had with Cohen and others, including foreign nationals, regarding real estate developments in Russia during the campaign.

But Trump lawyer Rudy Giuliani told Fox News' Catherine Herridge there is no "contradiction" with Trump's answers and they "remain comfortable" with the president's responses.

Trump, in response to Thursday's plea deal, called Cohen a "weak person" and accused him of lying to get out of trouble.

There was nothing at all illegal about the Trump Organization negotiating a real estate development deal with Russia or anyone else during the campaign, or even in office, for that matter.  Perhaps Cohen misremembered the date the talks ceased, or perhaps he was  trying to avoid embarrassment.  That embarrassment was not because of any illegality or impropriety, but rather, it has to do with keeping up appearances of confidence in victory.  It seems obvious that President Trump was hedging his bets, not 100% certain that his campaign would bring victory (as 99%-plus of the media and "experts" predicted), and not torpedoing the process of exploring new business projects, a steady of stream of which is necessary to maintain his activity as a developer.

Trump tweeted this just a few hours ago, from Argentina.

Oh, I get it! I am a very good developer, happily living my life, when I see our Country going in the wrong direction (to put it mildly). Against all odds, I decide to run for President & continue to run my business-very legal & very cool, talked about it on the campaign trail...

— Donald J. Trump (@realDonaldTrump) November 30, 2018

....Lightly looked at doing a building somewhere in Russia. Put up zero money, zero guarantees and didn’t do the project. Witch Hunt!

— Donald J. Trump (@realDonaldTrump) November 30, 2018

No less than lifelong Democrat and Hillary Clinton voter Alan Dershowitz is pointing out that rather than uncovering past crimes, Mueller's modus operandi is to generate new crimes in the course of investigation:

The recent guilty plea of Michael Cohen of lying represents the dominant trend in Mueller's approach to prosecution.  The vast majority of indictments and guilty pleas obtained against Americans by Mueller have not been for substantive crimes relating to his mandate: namely, to uncover crimes involving illegal contacts with Russia.  They have involved indictments and guilty pleas either for lying, or for financial crimes by individuals unrelated to the Russia probe.  If this remains true after the filing of the Mueller report, it would represent a significant failure on Mueller's part.

Mueller was appointed Special Counsel not to provoke individuals into committing new crimes, but rather to uncover past crimes specifically involving alleged illegal coordination between the Trump campaign and Russian agents.  No one doubted that Russia attempted to influence the 2020 election in favor of Donald Trump and against Hillary Clinton.  But Mueller's mandate was not to prosecute Russians or to point the finger at Vladimir Putin.  His mandate was to uncover crimes committed by the Trump campaign with regard to Russia's attempts to influence the election.

Meanwhile, actual evidence that the Hillary Clinton campaign colluded with Russian intelligence agents (via cutouts Perkins Coie and Fusion GPS) to influence the election is apparently of no interest whatsoever to Mueller.  It's almost as if this entire effort is a cover-up...