A Missouri initiative to establish a top-four system is circulating. This St. Louis Post-Dispatch article says over $1,000,000 has been contributed by a Virginia group that refuses to disclose its donors.
The Missouri initiative makes it far more difficult for parties to attain or keep qualified status. Currently a party in Missouri is a group that polled at least 2% for any statewide race in either of the last two elections. The initiative changes this, so a party could only remain ballot-qualified if it polled 2% for president. Thanks to Fairvote for the link.