Sam Rankin of Billings, Montana, will attempt to get on the ballot this year as an independent candidate for U.S. Senate in Montana. See this story. No one has qualified as an independent candidate for U.S. Senate in Montana since 1936. Since 1895, Montana has had very severe ballot access laws for non-presidential independent candidates. The law requires signatures equal to 5% of the winning candidate’s vote in the last election. Rankin will need 17,417 valid signatures by May 27.
The deadline was formerly in March, but that deadline was declared unconstitutional in 2012 in Kelly v McCulloch, so the legislature moved it to May. It is conceivable that the May petition deadline is also unconstitutionally early. The primary is June 3. Generally it is unconstitutional for states to require independent candidates to file petitions before the primary.
Ironically, if Rankin had decided to run as the nominee of a new party, he would only need 5,000 signatures, but the deadline for that petition is March 13. Thanks to Mike Fellows for this news.