Four states will hold votes on ballot initiatives to legalize recreational or medical marijuana on election day, and yet vulnerable Democrats in those states aren't using to their advantage.

While many believe marijuana ballot initiatives in Utah, Michigan, North Dakota and Missouri will bring out many younger, more liberal voters to the polls, Democrats aren't capitalizing on that interest. This is particularly true in Missouri and North Dakota, where incumbent Democratic senators are facing incredibly tough bids for re-election.

In North Dakota, incumbent Democratic senator Heidi Heitkamp has largely ignored her state's marijuana initiative, refusing to even give her position on it to one newspaper. This is despite a recent poll showing the initiative may actually win, and other polls showing Heitkamp is on track to lose her re-election bid.

The same is true in Missouri where incumbent Democratic senator Claire McCaskill is facing a toss-up re-election race. McCaskill has tepidly endorsed medical marijuana, but she's not endorsed any of the three medical marijuana initiatives in Missouri. And considering her opponent opposes medical marijuana, that would seem to be a good issue for her to win a few more votes.

Perhaps the two senators think that the marijuana initiatives will already bring out more progressive-minded voters who will vote for them anyways, so they don't think they need to make appeals to pro-cannabis voters. But if they end up losing their elections while their state's marijuana initiatives succeed, then perhaps the whole party will begin re-thinking its strategy towards marijuana.

(h/t RollCall)