Those who contribute $3 or more to the effort to defeat Minnesota’s proposed marriage amendment have a chance to win an interesting prize: a voicemail message recorded by radio host and author Garrison Keillor.

Minnesotans United for All Families, which has organized opposition to the marriage amendment, is running the contest.

The donation deadline for a chance at the prize is 6 p.m. July 18.

One Facebook commenter wondered if retired newscaster Carl Kasell, who records voicemail messages for winners on NPR’s “Wait, Wait  … Don’t Tell Me,” wasn’t available.