The tone of the campaign for the 28th District turned sour on its final day, with Stammreich and the California Republican Party filing complaints accusing the Democratic Party and Secretary of State Debra Bowen of using a late-hour campaign mailing to "illegally influence" voters to cast a ballot for Oropeza.

The correspondence, titled "Election Information," was sent via mail to Democratic and decline-to-state voters and outlined what would happen if Oropeza won.