Responding to reports that President Donald Trump claims to not have any recordings of his conversations with fired FBI Director James Comey as he claimed last month on Twitter, a former White House ethics lawyer said being caught in this lie opens the president up to obstruction of justice.

“This lie increases Trump’s legal exposure for obstruction and witness intimidation–more evidence of corrupt intent,” Norm Eisen, who served as special counsel to President Barack Obama and later as an ambassador to the Czech Republic, tweeted.

The lie Eisen referred to was tweeted by the president on May 12, when he threatened that “James Comey better hope that there are no ‘tapes’ of our conversations before he starts leaking to the press!”

On Thursday, Trump took to Twitter again to admit that he “did not make, and do[es] not have, any such recordings.”

Read Eisen and Trump’s tweets below.

James Comey better hope that there are no “tapes” of our conversations before he starts leaking to the press!

— Donald J. Trump (@realDonaldTrump) May 12, 2017

…whether there are “tapes” or recordings of my conversations with James Comey, but I did not make, and do not have, any such recordings.

— Donald J. Trump (@realDonaldTrump) June 22, 2017

This lie increases Trump’s legal exposure for obstruction and witness intimidation–more evidence of corrupt intent @Susan_Hennessey https://t.co/qBx7e58XEl

— Norm Eisen (@NormEisen) June 22, 2017