| MIKULSKI FOR CONGRESS | $275K | 6 | 1986 |
| DEMOCRATIC STATE CENTRAL COMMITTEE OF MARYLAND | $237K | 15 | 1986, 1998, 2004, 2010 |
| DSCC | $181K | 9 | 1986, 1992 |
| AMERICAN FEDERATION OF STATE COUNTY & MUNICIPAL EMPLOYEES P E O P L E | $55K | 25 | 1986, 1988, 1992, 1998, 2002, 2004, 2010, 2014, 2016 |
| INTERNATIONAL ASSOCIATION OF SHEET METAL, AIR, RAIL AND TRANSPORTATION WORKERS POLITICAL ACTION LEAGUE | $50K | 16 | 1986, 1990, 1992, 1998, 2004, 2010, 2014 |
| UAW - V - CAP (UAW VOLUNTARY COMMUNITY ACTION PROGRAM) 'INT'L UNION UNITED AUTOMOBILE AEROSPACE & AGRICULTURAL IMPLEMENT WORKERS OF AMERICA UAW | $50K | 19 | 1986, 1990, 1992, 1998, 2002, 2004, 2008, 2010 |
| AMERICAN ASSOCIATION FOR JUSTICE POLITICAL ACTION COMMITTEE (AAJ PAC) | $47K | 25 | 1986, 1992, 1994, 1996, 1998, 2000, 2002, 2004, 2006, 2008, 2010, 2014 |
| NATIONAL ASSOCIATION OF LETTER CARRIERS OF U.S.A. POLITICAL FUND (LETTER CARRIER POLITICAL FUND) | $47K | 19 | 1986, 1990, 1992, 1998, 2004, 2006, 2008, 2010 |
| MACHINISTS NON PARTISAN POLITICAL LEAGUE OF THE INTERNATIONAL ASSOCIATION OF MACHINISTS & AEROSPACE WORKERS | $47K | 13 | 1986, 1990, 1992, 1998, 2004, 2010 |
| NATIONAL ASSOCIATION OF SOCIAL WORKERS INC. POLITICAL ACTION FOR CANDIDATE ELECTION (PACE) | $46K | 24 | 1986, 1990, 1992, 1998, 2002, 2004, 2008, 2010, 2012 |