Donald Trump's attorney general has already proved he is willing to lie under oath.

The last time Attorney General Jeff Sessions testified before the Senate, when he was still a senator from Alabama seeking to lead the Department of Justice, he lied under oath. And now he might do it again.

Sessions has agreed to testify publicly Tuesday afternoon before the Senate Select Committee on Intelligence. Whether his testimony will be under oath has not yet been announced. But the last time he testified, it was under oath. And that testimony later proved to be false.

During his confirmation hearing, Sessions was questioned by Democratic Sens. Patrick Leahy of Vermont and Al Franken of Minnesota about contacts he’d had with Russian officials. Sessions denied it at the time, but subsequent reports showed that Sessions did indeed have meetings he failed to disclose.

When that was revealed, Franken said Sessions had “perjured himself.” Leahy recently said that “Sessions provided false testimony” to him and to Franken. Other Democrats called for his resignation. Republicans refused to support calls for Sessions’s resignation; nonetheless, the pressure from Democrats did lead to the attorney general being forced to recuse himself from related investigations.

Now that Sessions is finally about to testify before the Senate again — after resisting calls to do so — serious questions exist about whether he will be honest in his testimony.

Sessions had previously agreed to testify publicly before the Senate Committee on Appropriations, which has oversight responsibilities for the Department of Justice. However, he then changed his mind and canceled his appearance, citing what he claimed were committee members’ “intention to focus their questions on issues related to the investigation into Russian interference.”

Leahy blasted Sessions on Twitter for canceling the appearance, telling him, “You can’t run forever.”

Sessions then conceded and one more agreed to testify publicly, though before a different Senate committee — one on which, perhaps not coincidentally, neither Leahy or Franken sit.

During former FBI Director James Comey’s public testimony before the intelligence committee last week, he highlighted Sessions’s role in the Trump team’s connections with Russia and hinted at more that could not be revealed in a public setting.

In the private, classified meeting that followed, Comey reportedly told senators of yet another, undisclosed meeting between Sessions and Russian government officials — bringing the total known number of Sessions’ covert contacts with the Russian government to three, so far. Comey’s public and private testimony led veteran journalist Dan Rather to characterize Sessions as a “marked man.”

Democrats on the intelligence committee certainly know they have a huge task before them when Sessions testifies on Tuesday. After all, they already know how willing he is to lie to them.