Unions do contribute to pro-labor candidates and incumbents. If someone objects they should move to support campaign finance reform and condemn the USSC members who voted for Citizens United v. FEC. The should demand a Constitutional Amendment preventing political donations of any kind.
Please explain how it is a "right" to have collective bargaining
Amendment 1 - Freedom of Religion, Press, Expression. Ratified 12/15/1791. Note
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.
In black and white.
Yep, that includes Business too.