On August 3, the Idaho Secretary of State wrote a letter to Darrell Castle, saying the office believes he is circulating an independent presidential petition, and warning him that if he submits the required 1,000 signatures by the August 24 deadline, the office will reject it because sec. 34-708A says that independent presidential candidates must declare that they have no political party affiliation. This law has existed since 1977, and yet always before it has been interpreted to refer to political party affiliation for Idaho parties, not national parties or parties in other states.
On August 10, Castle responded with this letter. Castle notes that John Anderson was permitted to be on the Idaho ballot as an independent in 1980, even though Anderson continued to list himself as a Republican in his Congressional Directory page all during 1980. Castle notes that Idaho let Jill Stein be an independent presidential candidate in 2012, even though at the time, and currently, she is a registered Green in Massachusetts. Castle noted that Idaho let Rocky Anderson be an independent presidential candidate while he was a registered Justice Party member in Utah.
Finally, Castle notes that he himself is not a registered member of the Constitution Party, because he lives in Tennessee, which does not have registration by party. Also the Constitution Party does not have dues-paying membership.
The reason Castle has been circulating an independent petition in Idaho is because the ballot-qualified Constitution Party in Idaho is lead by individuals who are angry with the national Constitution Party, so they won’t put Castle on as the party nominee.