Alison Green writes in U.S. News & World Report:
"'Private-sector employers may generally impose broad limits on employees' political activities and discussions during working hours, even if other types of personal activities are permitted,' says Dan Prywes, partner in the District of Columbia office of the law firm Bryan Cave.
"However, federal law also protects employees' right to discuss labor issues -- wages and working conditions -- with each other. So employers need to tread carefully here. They can't ban you from urging co-workers to support Candidate X 'because she supports higher wages.' But those same protections don't apply if you take labor issues out of the discussion. For instance, you're urging people to support Candidate X 'because she's strong on foreign policy' or for another reason not connected to labor issues."
In other words, when discussing our free speech rights, we must remember the first words in the First Amendment: "Congress shall make no law ...." That is, the government is prohibited from "abridging the freedom of speech."
Here's the entire amendment, all about what the government cannot do: "Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof; or abridging the freedom of speech, or of the press; or the right of the people peaceably to assemble, and to petition the Government for a redress of grievances."