COLUMBUS, Ohio (AP) -- A national union leader says Ohio coal miners pictured in a new ad from the Mitt Romney campaign are those who were required to appear at the Republican presidential nominee's coal-country rally, missing a day's pay.
AFL-CIO President Richard Trumka on Wednesday echoed earlier concern after footage from the August event at the Century Mine in Beallsville in southeastern Ohio was included in Romney's ad.
The AFL-CIO has sought an investigation into the plant being shuttered for the rally.
The ad criticizes President Barack Obama for imposing environmental regulations that have hurt coal and for a 2008 remark that new coal-fired power plants would go bankrupt as a result of fees on greenhouse gas emissions.
A Romney campaign spokesman noted the nation's largest coal mining union has not endorsed Obama.