After months of sometimes bitter wrangling between the staff and management, workers for the liberal media watchdog group Media Matters for America voted Monday to join the Service Employees International Union.

“I am thrilled that the employees at Media Matters have chosen to join us at SEIU Local 500. Nonprofits like Media Matters have always been an important part of the larger progressive movement – now their employees are joining their colleagues at organizations like Public Citizen, Oxfam and the United States Student Association as a growing part of the labor movement,” said Merle Cuttitta, the local’s president, in a statement posted on its website.