Former Vice President and climate activist Al Gore took to Twitter on Thursday to express his disgust for a fradulent lobbying effort during the debate over cap-and-trade legislation this summer.

In June, a coal group had known of forged letters critical of the climate legislation sent by a firm hired by a contractor to Democratic members of Congress. The letters were allegedly from local nonprofit groups.

Though the American Coalition for Clean Coal Energy knew of the forgery, they delayed notifying the affected members until well after the vote. 

Gore tweeted:

This disgusts me

The former VP linked to a blog post in which he said "this subversion of our democracy is disgusting. The fact that members of the House of Representatives went to the floor to vote on the climate bill with false information is unacceptable."

The House eventually passed the legislation, which the Senate is now working to complete.

"As the Senate begins work on this issue, members should view communications from lobbying groups opposing climate and green jobs legislation with increased skepticism," Gore added.