(CNN) Former Vice President Al Gore will hit the campaign trail for Hillary Clinton in the coming weeks, two senior Democrats sources told CNN on Tuesday.

Democratic presidential candidate Gov. Bill Clinton, left, waves to the crowd with Sen. Al Gore on July 9, 1992, after announcing Gore as his vice-presidential nominee in Little Rock, Arkansas.

Democrats are hoping that Gore, who served with Clinton's husband during his administration, can help the Democratic presidential nominee appeal to millennial voters who are concerned about climate change.

With polls suggesting that third-party candidates including Gary Johnson and Jill Stein could potentially tip the election to Donald Trump if the final vote is close, Democrats are hoping that Gore can make the case that voting for an alternative candidate can have lasting consequences -- a not so subtle reminder that Green Party candidate Ralph Nader may have tipped Florida from Gore to George W. Bush in 2000.