AUGUSTA – Gov. Angus King vetoed a bill Friday that was designed to ban permanent replacement workers in a labor dispute.

The proposal would require that contracts between employers and replacement workers assure that when a strike is settled or employees offer unconditionally to return to work, the replacement workers will not be retained instead of the strikers.

King has vetoed similar legislation in the past.

In a formal message to the Legislature, King said he judged a portion of the bill to be unconstitutional.

He also said he believed its enactment “would send a false message to the working community in Maine in that it unreasonably raises the hopes of workers that the state has a role to play in federally regulated labor issues.”

King added that “the hiring of permanent replacement workers, particularly in the early stages of a strike, is not a tactic I would encourage or support.”

The measure was approved in the House by a vote of 96-45 and in the Senate by a vote of 18-16. Majorities of two-thirds in both chambers would be needed to override the veto.