Is a president's willful lying impeachable?

Is a president's deliberate lying impeachable? I am asking the question to attorneys in the audience. President Trump and his spokespersons continually speak untruths. When confronted with contradictory facts, they parry them away with "alternative facts." The alternatives are disproven, yet the President and company persist in repeating falsehoods that are lies.

Now, what is a nation to do about this? The President speaks from a bully pulpit spewing lies. Is there no legal recourse?

"All presidents lie. Richard Nixon said he was not a crook, yet he orchestrated the most shamelessly crooked act in the modern presidency. Ronald Reagan said he wasn’t aware of the Iran-Contra deal; there’s evidence he was. Bill Clinton said he did not have sex with that woman; he did, or close enough. Lying in politics transcends political party and era. It is, in some ways, an inherent part of the profession of politicking. 

But Donald Trump is in a different category. The sheer frequency, spontaneity and seeming irrelevance of his lies have no precedent. Nixon, Reagan and Clinton were protecting their reputations; Trump seems to lie for the pure joy of it. A whopping 70 percent of Trump’s statements that PolitiFact checked during the campaign were false, while only 4 percent were completely true, and 11 percent mostly true. (Compare that to the politician Trump dubbed “crooked,” Hillary Clinton: Just 26 percent of her statements were deemed false.)" 

http://www.politico.com/magazine/story/2017/01/donald-trump-lies-liar-effect-brain- 

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I am the greatest liar in the world.

https://www.youtube.com/watch?v=dec_Yt2yns8