Al GoreAlbert (Al) Arnold GoreJoe Lieberman: We’re well beyond partisanship, our national government has lost civility Trump doesn't start a trade war, just fires a warning shot across the bow Dems face hard choice for State of the Union response MORE says Democrats should "wait" for former FBI Director Robert Mueller to wrap up his investigation before suggesting President Trump may have committed treason.

"Anything having to do with the investigation, I think people ought to wait for Bob Mueller to conduct his investigation," the former vice president told ITK, when asked whether Democrats accusing Trump of treason are going too far.

The Justice Department appointed Mueller in May as special counsel to investigate Russia's involvement in last year's presidential election.

Democrats have increasingly raised worries about recent revelations of Trump campaign officials' meetings with Russians. Sen. Tim KaineTimothy (Tim) Michael KaineSave lives, restore congressional respect by strengthening opioids’ seizure Overnight Finance: Lawmakers, Treasury look to close tax law loopholes | Trump says he backs gas tax hike | Markets rise despite higher inflation | Fannie Mae asks for .7B Bipartisan Senate group says they have immigration deal MORE (D-Va.) last week suggested Mueller's investigation is now looking into possible "treason." And Rep. Brad Sherman (D-Calif.) filed a formal article of impeachment against the president.

Gore returned to the nation's capital on Wednesday for the premiere of "An Inconvenient Sequel: Truth to Power" at the Newseum in Washington.

The film, which hits theaters nationwide on Aug. 4, is a follow-up to his groundbreaking 2006 climate change documentary, "An Inconvenient Truth."

Asked whether he's personally frustrated about the need for an "Inconvenient" sequel, Gore replied, "There have been two big changes in the last decade: the extreme weather events related to climate are much more numerous, much more destructive."

"But the good thing is, the solutions are here now," Gore continued. "We have what we need to solve this and we can create jobs and build the economy at the same time — so that's the good news."