Free Speech, employment
Letter by co-worker sufficient proof that employer was aware of political affiliation.
Genuine issue of material fact as to whether adverse employment actions created a cause of action.
Bona fide reason for ending of employment does not mean that there is no issue of material fact as to whether the ending of employment would have happened but for the political speech.
http://media.ca1.uscourts.gov/pdf.opinions/14-2172P-01A.pdf
Since 2011. An occasional commonplacing of the U.S. Circuit Courts of Appeal.
Neither an authoritative statement of the law nor legal advice. Quick work.