Former Vice President Al GoreAlbert (Al) Arnold GoreVoting mentality of seniors shifting ahead of midterms, says Morning Consult editor Nikki Haley powerfully rebuts Trump No, civility isn't optional MORE today warned that Democrats could see another candidate fall just short of the White House if supporters do not work hard to push Barack ObamaBarack Hussein ObamaBiden jokes about Obama memes: 'Barack did the first friendship bracelet, not me' Slain Saudi columnist upends 'Davos in the Desert' Sanders, Harris set to criss-cross Iowa MORE toward victory between now and Nov. 4

Gore sent an e-mail to MoveOn.org supporters this afternoon, urging them to volunteer for Obama's campaign and using 2000 as a cautionary tale.

"Barack Obama is rising up to unite America behind his vision of progressive change. Yet we know from 2000 that progress is not inevitable. Victory can fall just out of reach. And the difference of a few thousand votes can put our country on a decidedly different path," Gore wrote.

"That's why I'm writing to you today to personally ask you to volunteer with the Obama campaign to help get out the vote this week. Everything we've worked for together hangs in the balance in these next few days," the former vice president continued.

Gore has largely stayed out of the limelight of the 2008 campaign aside from his highly publicized endorsement of Obama in June.