Franken's comments on CNN's "Erin Burnett OutFront" came after unsealed court documents showed
former Trump campaign adviser George Papadopoulos had told the campaign about a potential meeting opportunity between Donald Trump and Russian President Vladimir Putin, and news emerged
that Sessions vetoed the idea.
"He seems to have problems telling the truth on this subject," Franken said of Sessions.
The Justice Department did not immediately respond to a request for comment Thursday evening.
During Sessions' confirmation hearing, Franken asked if he knew of contacts between the Trump campaign and Russia, and Sessions said he had not had meetings with Russians during the campaign. After reports to the contrary, the Justice Department clarified Sessions met with the Russian ambassador twice, and former FBI Director James Comey said Sessions may have met with the ambassador a third time.
Sessions later recused himself
from all matters related to the campaign, citing his support for the President's successful bid.
before the Senate Judiciary Committee again in October.
Franken said he thought Sessions vetoing a meeting with Putin would be "something you'd remember" and wanted Sessions to testify again. However, he declined to say whether he thought Sessions lied and said he thought any decision on whether Sessions did something wrong should be left with special counsel Robert Mueller.
"Ultimately, whether or not he committed perjury, will be again, I believe, Bob Mueller's call," Franken said.
Former Trump campaign adviser Carter Page privately testified
on Thursday that he had mentioned to Sessions that he was traveling to Russia in July 2016.
Franken also said Mueller is "obviously" looking at potential obstruction of justice around the firing of Comey and that he believed Mueller would "get to the bottom" of that issue as well.
The Democratic senator said he did not know White House adviser Jared Kushner's role in the firing, and declined to weigh in on any potential wrongdoing on Kushner's part, including Kushner's multiple amendments to his security clearance form.
"It's odd that he forgot all those things," Franken said.