Labor Unions
- Brotherhood of Locomotive Engineers and Trainmen*
- International Union of Operating Engineers Local 513*
- LiUNA Missouri and Kansas Laborers District Council*
- Mid-America Carpenters Regional Council*
- Sheet Metal Workers Local Union No. 36*
- Teamsters Local Union 41*
- Teamsters Local Union 541*
- Teamsters Local Union 688*
Organizations
- Sierra Club*
- Access MO*
- Planned Parenthood Great Plains Votes
Individuals
- Jennifer Arnold*
- Kay Callison*
- Kari Chesney Siegler*
- Elisabeth Condon*
- Persephone Dakopolos*
- Dee Dokken*
- Deborah Finley*
- Dennis Hodo*
- Howard Hutton*
- Hank Ottinger*
- David Robinson*
- Dr. Jacque Sample*
- Lindsey Simmons*
- Michela Skelton*
- Dr. George Smith*
- Pam Springsteel*
- Al Tacker*
- Hallie Thompson*
- Herb and Sue Tillema*
- Alyce Turner*
- Laura Wacker*
*indicates a sole endorsement of Adrian Plank over his primary opponent
