Now it's his turn, touring for the 21-year-old nonprofit group in an effort to encourage thousands of young people to register to vote.
"It's not just about ... smiling and waving," says Mraz, in a videotaped interview. "There has to be a purpose for us being out here. And I feel I'm in a unique position to shine a little light, a little love, a little awareness -- and obviously some resources."
He's not alone. Designers and entrepreneurs of all political persuasions are trying to get out the vote this election season -- by getting out the merchandise. T-shirts, hoodies, boxers, onesies -- even the most patriotic of manicures -- with stars, stripes or the little teeny mugs of Romney or Obama on your nails -- can be yours if you're looking to flaunt some electoral flair.
For designer and longtime social activist Kenneth Cole, this is a chance to highlight an important cause.
"In 2008, six million Americans did not get the opportunity to vote," he says, "because they either missed the opportunity to register or didn't know how to."
Cole is donating all profits from a limited-edition $20 tote bag to his Kenneth Cole Foundation to support voter registration efforts. You can learn more about what you can do (and see Mraz' interview) on the foundation's website, awearness.com.
As for the best of what's red, white and blue-ish, we've collected it here. So browse ... shop ... then vote.
Republican, Democrat ... who doesn't heart Abe? And now, just in time for the new Steven Spielberg biopic starring Daniel Day-Lewis (which hits theaters just after Election Day), Studio Penny Lane offers a new "Big Abe" collection of tees featuring Lincoln's name, likeness and quotations; $44 to $48 at studiopennylane.org.