AUGUSTA — Republicans’ efforts to make Maine a so-called “right-to-work” state failed, again, on Monday with a 21-14 vote against the concept in the Senate.

LD 489 was already on life support following a 90-52 House of Representatives vote against it last week. The bill would have prevented organized labor unions from collecting representation fees as a condition of employment.

Making Maine a right-to-work state has been a priority of Gov. Paul LePage and many Republicans for years. Legislation similar to the bill that was killed Monday was also unsuccessful in 2011, despite Republican majorities in the House and Senate, and 2013. Two years ago, LePage called his inability to pass right-to-work his “biggest failure” since being elected governor.

A senior economic adviser for LePage told lawmakers earlier this year that right-to-work is vital if Maine wants to compete globally.

“Becoming a right-to-work state is just one piece of the puzzle Maine must embrace if we want to be competitive and attract investment and quality job opportunities,” said John Butera.

Opponents say right-to-work laws are an attempt to undermine the bargaining power of unions and drive down wages. They noted that efforts to make Maine the first New England state to adopt a right-to-work law have failed repeatedly, even when Republicans controlled both chambers of the Legislature in 2011.

“I’m thankful that common sense prevailed in the past,” said Democratic Sen. John Patrick of Rumford, former president of the United Paperworkers Union Local 900. “I don’t believe that anything has changed.”

But supporters said the bill is about freeing workers from the “shackles of compulsory unionism.”

“Right-to-work laws give workers a choice over where their money goes,” said Republican Sen. Eric Brakey of Auburn. “This freedom forces unions to earn their members support and it also attracts businesses and jobs.”

Another anti-union bill, LD 404, would have prevented the state from deducting dues or representation fees from employees’ paychecks. That bill also died Monday in a 23-12 Senate vote. Two other bills are still pending, though votes against them in the House last week mean they are also likely dead.

Information from the Associated Press was used in this report.