DENVER -- Opponents of Denver’s latest impound initiative are manning phone banks and going door-to-door in a last-minute effort to educate people about what they call the measure’s “unintended consequences.”

Initiative 300 would force police officers to impound the car of any driver who doesn’t have a driver’s license.

Opponents said because of the initiative’s vague language, people who have left their licenses at home could get their cars towed and have to pay $2,700 to get them back.

The initiative requires people who’ve left their license at home to show proof of insurance, a license of record and “convincing corroborating identification.”

“Lawyers we’ve talked to say that means government issued identification -- such as a passport,” said Jessie Ulibarri with Coloradans for Safe Communities, a group opposing the initiative. “But if you’ve forgotten your wallet at home, you’re probably not driving around with your passport.”

The initiative’s proponents say it’s up to the discretion of the officer.

"If they know their birthday, Social Security number and fit the description, I can't imagine them being towed," said Dan Hayes. “But it is vague, I guess in a sense. But so many laws are.”

If you haven’t mailed your ballot yet, you can drop it off inside the Wellington Webb Building or at the Denver Elections Division on Monday or Tuesday.