The Free Beacon  doing some great work on the subject:
Three of the nation’s largest unions—the American Federation of State, County, and Municipal Employees (AFSCME), United Food and Commercial Workers (UFCW), and Service Employees International Union (SEIU), contributed $435,000 to the nation’s largest abortion provider.
Almost all of that money was spent on political advocacy. AFSCME donated $400,000 to the Planned Parenthood Action Fund, which spent about $1 million helping Democratic campaigns in 2014, according to the Center for Responsive Politics . UFCW categorized its $10,000 donation as political activity in federal labor filings.