Pete Buttigieg's presidential campaign announced a new contest to drum up fundraising: who can give the Democratic candidate the lowest contribution.

In a email to supporters Tuesday evening, Buttigieg's campaign wrote that the donor who contributes the lowest amount in the hours ahead - provided that no other donor matches the contribution amount - will win a prize from the campaign.

"All you have to do to win is donate the smallest amount that nobody else donates," reads the email. "Multiple donations are allowed; just be creative, pick a unique donation amount, and you could win."

Some Twitter users pointed out that the effect of the contest would be to lower the South Bend, Ind., mayor's average donation amount. Other candidates, including Sen. Bernie Sanders (I-Vt.), have frequently touted their low average donations on the debate stage to highlight grassroots support for their campaigns.

"The Pete for America Innovation Team out there working hard on Christmas Eve coming up with gimmicks to lower his average donation amount this quarter. Funny stuff," wrote Tim Tagaris, a senior adviser to the Sanders campaign.

"This is so transparently hilarious. Wow, his average donation was lower this quarter... it's a Christmas miracle!" Tagaris added.

The fundraising contest comes just days after Buttigeig faced heat from his fellow Democrats onstage at Thursday's Democratic debate over a fundraiser in a wine cave, which was pilloried by rivals such as Andrew Yang and Sen. Elizabeth Warren (D-Mass.) as an effort to sway big donors to Buttigieg's campaign while opening up the mayor to special interests.

Buttigeig and Warren in particular have been battling ahead of the Iowa caucuses.

The battles over fundraising and donors have prompted new scrutiny of both campaigns. On Tuesday, The Washington Post published a story that focused on contributions from bigger donors that Warren had taken before her presidential campaign.