| SUPER PAC FOR AMERICA | $87K | 3 | 2010 |
| MACHINISTS NON PARTISAN POLITICAL LEAGUE OF THE INTERNATIONAL ASSOCIATION OF MACHINISTS & AEROSPACE WORKERS | $75K | 17 | 2010, 2024, 2014, 2020, 2016, 2012, 2018, 2022, 2008 |
| AMERICAN FEDERATION OF TEACHERS, AFL-CIO COMMITTEE ON POLITICAL EDUCATION | $73K | 17 | 2010, 2024, 2014, 2020, 2016, 2012, 2018, 2022, 2008 |
| NATIONAL ASSOCIATION OF REALTORS POLITICAL ACTION COMMITTEE | $71K | 34 | 2010, 2024, 2014, 2020, 2016, 2012, 2018, 2022, 2008 |
| GENERAL DYNAMICS CORPORATION POLITICAL ACTION COMMITTEE (GENERAL DYNAMICS EMPLOYEE PAC) | $67K | 39 | 2010, 2024, 2014, 2020, 2016, 2012, 2018, 2022, 2008 |
| PROGRESSIVE TURNOUT PROJECT | $66K | 2 | 2018, 2022 |
| LABORERS' INTERNATIONAL UNION OF NORTH AMERICA (LIUNA) PAC | $63K | 17 | 2010, 2024, 2020, 2016, 2012, 2018, 2022, 2008 |
| NEA FUND FOR CHILDREN AND PUBLIC EDUCATION | $57K | 22 | 2010, 2024, 2014, 2020, 2016, 2012, 2018, 2022, 2008 |
| MAINE DEMOCRATIC PARTY | $56K | 5 | 2022, 2008 |
| AMERICAN ASSOCIATION FOR JUSTICE POLITICAL ACTION COMMITTEE (AAJ PAC) | $56K | 27 | 2010, 2024, 2020, 2016, 2012, 2018, 2022, 2008 |