WASHINGTON (AP) — The Supreme Court is hearing arguments in a case that could deal a painful financial blow to organized labor.

All eyes will be on Justice Neil Gorsuch Monday when the court takes up a challenge to an Illinois law that allows unions representing government employees to collect fees from workers who choose not to join. The unions say the outcome could affect more than 5 million government workers in 24 states and the District of Columbia.

The court split 4-4 the last time it considered the issue in 2016. Gorsuch joined the court in April and has yet to weigh in on union fees. Organized labor is a big supporter of Democratic candidates and interests. Unions strongly opposed Gorsuch's nomination by President Donald Trump.

Illinois government employee Mark Janus says he has a constitutional right not to contribute anything to a union with which he disagrees. Janus and the conservative interests that back him contend that everything unions representing public employees do is political, including contract negotiations.