Doug Burgum is giving $20 gift cards in exchange for campaign donations. Experts split on whether that's legal

For the last couple weeks, it's been profitable to donate to North Dakota Gov. Doug Burgum's presidential campaign. New donors stood to gain a handsome profit of $19, since those who sent at least $1 were promised a $20 Visa or Mastercard mailed to their address by the Burgum campaign in exchange for their donation.

The gift card giveaway has cost the campaign hundreds of thousands, but it helped Burgum cross the 40,000 unique-donor threshold to help him secure a microphone at the first Republican presidential primary debate in Milwaukee next month. There, he would have a chance to reach his largest audience yet. Burgum's small donors skyrocketed after the new promotional ploy: within just 48 hours of starting the promotion last week, the campaign had 20,000 new donors.