The competition to succeed state Sen. Richard Devlin (D-Tualatin) is one of the most complex, hotly contested and consequential metro-area legislative appointments in many years.

One sign of how meaningful it is: Unions and trial lawyers are taking the unusual step of endorsing choices for a seat that’s appointed by county commissioners.

The American Federation of State, County and Municipal Employees, Service Employees International Union and the Oregon Education Association will join the Oregon Trial Lawyers Association in making endorsements because they hope to tilt the balance of the Senate leftward.

They’ll have plenty of people to choose from: Recently retired Multnomah County lobbyist Claudia Black entered the race Nov. 21, joining, among others, Lake Oswego School Board member Rob Wagner and former state Rep. Greg Macpherson (D-Lake Oswego).