Vos and more than a dozen state legislators have already endorsed Rubio. Those who pay $100 to attend the Burlington event will have a chance to join Rubio for a general reception while those who pay $500 will get a photo with the Florida senator, according to a copy of the invitation provided to The Washington Post. Supporters willing to part with $2,500 will be invited to a private "roundtable discussion" with Rubio attended by only about two dozen people.
Before attending the Rubio event, Walker plans to join Bush at a joint appearance at a private charter school in Waukesha.
Sean Sullivan contributed to this article.