Katy Perry knows who she's voting for in the upcoming election.

She wore a crafty tight white dress with a ballot on it last night (Oct. 24) during a campaign rally concert in Las Vegas, Nevada, and checked Barack Obama and Joe Biden's names off. Mitt Romney's name was left blank.

"Don’t wait, go tomorrow,” she said, urging the 13,000 people in attendance to vote between performing a handful of her hits. “How many of you guys are 18 in here? Let’s do this tomorrow. You know I got my poll outfit sorted."

Nevada is a hotly-contested battleground state in the upcoming election and right now polls suggest that its divided on which candidate to vote for. Obama won Nevada in 2008. Maybe Katy Perry's endorsement will help push him into the lead.

[via NY Daily News]