He doesn't need Trump to call him a liar. The U.S. Government has already done that and is going to use prison as an exclamation point.
Yeah, for lying for Trump, at the direction of Trump. What part of that is not understood?
Let me break it down for you and apparently others...
Cohen lied for Trump, at the direction of Trump.
Cohen got caught in the lie through the investigation of Robert Mueller, which he handed it off to the Southern District of NY.
The FBI raids Cohen. (Trump calls this warranted raid a "witch hunt", an "attack on our Country in a true sense", and he spoke about firing Mueller afterwards)
Cohen pleads guilty to lying for Trump, at the direction of Trump.
He gets sentenced to 3 years in prison.
He has already been sentenced, he likely doesn't want more years added to it (The FBI & the SDNY knows if he's lying, remember the raid from earlier).
Again...for those in the back. COHEN GOT CAUGHT, LYING, BY MUELLER, FOR TRUMP, AT THE DIRECTION OF TRUMP!!!!
Now, Trump Jr. is likely about to get hit with a subpoena regarding the check that he signed to pay Cohen, from the Trump organization. Off topic, what was the name of the Uncle in the Napoleon Dynamite movie?