According to the Congressional Quarterly, the White House stated on Tuesday that President Bush would veto the HHS-Labor-Education Appropriations Bill because of the cost and "objectionable provisions" such as a measure to ban the use of childhood flu vaccines that contain thimerosal, a mercury-based preservative.

Autism advocacy groups are outraged because President Bush stated in a questionnaire during his 2004 campaign: "I support the removal of Thimerosal from vaccines on the childhood national vaccine schedule. During a second term as President, I will continue to support increased funding to support a wide variety of research initiatives aimed at seeking definitive causes and/or triggers of autism. It is important to note that while there are many possible theories about causes or triggers of autism, no one material has been definitely included or excluded."