The Michigan AFL-CIO has endorsed Democratic gubernatorial candidate Virg Bernero, igniting a battle for union endorsements in the race.

The state AFL-CIO represents over 600,000 active and retired members in 59 unions throughout Michigan, including the United Auto Workers, the International Brotherhood of Electrical Workers, the American Federation of Teachers and the American Federation of State, County and Municipal Employees.

On Thursday, Democratic House Speaker Andy Dillon was endorsed by the Michigan Building and Construction Trades Council, which represents nearly 100,000 workers statewide.

Bernero, the mayor of Lansing, says the AFL-CIO endorsement adds greatly to his momentum.

State Rep. Alma Wheeler Smith also is running for the Democratic nomination.