U.S. Sen. Raphael Warnock’s campaign is pumping more than $1 million into an unconventional strategy to mobilize hard-to-reach Georgia voters before the Dec. 6 runoff against Republican Herschel Walker.

The Democrat’s “out of home” advertising campaign includes more than 100 billboards at high-traffic areas, a fleet of mobile signs deployed across the state and planes that tow messages above metro Atlanta that encourage Georgians to vote.

The campaign will also deploy posters at 28 college campuses, along with ads at transit stops, to encourage students to vote.

“These impossible to miss ads will complement our field work on the doors and the phones – and help ensure Georgia voters have all the information they need to vote for Rev. Warnock in the runoff,” said Warnock spokeswoman Sarafina Chitika.

The spending is part of an ever-growing advertising blitz ahead of a runoff that’s expected to drive significantly lower turnout than the November midterm. Walker’s campaign and his allies, too, have beefed up mobilization efforts that involve a spate of campaign stops in areas where voter participation lagged.