Could he still do that in the general?
I don’t know, it says the last day for Independent filings was June 12th. Of course, only left-wingers can avoid firm campaign laws (see: Loonie Lefty Lisa Murkowski). The only alternative might be to persuade a 3rd party nominee to step down and let Herrod be the nominee.
I see there will be three anti-Trump candidates: Curtis, the regular Dem, and the son of ex-Sen. Robert Bennett running on the Socialist Willardbot Egg McMuffin Party line. The IAP party candidate might be pro-Trump, but there’s no telling...