And it's not Matthew Lin, the Republican physician who is running against Chu's and Eng's choice, Democrat Ed Chau.
Chu, who was angry enough about the matter to call a news conference Thursday, is upset about Lin mailers that feature photos of Chu and Eng, as well as other Democratic elected officials who have not endorsed the Republican.
"Stop the shameful and unethical use of our names and pictures on your mailers!" Chu said she was publicly telling Lin. "We do not endorse you and we demand that you stop this immediately."
The mailers do not specifically say that Chu and the others endorse Lin, but Chu said voters could easily be misled.
"Is this the kind of person that we want to be our elected leader? Absolutely not," Chu said.
Some Lin supporters suspect that the dustup over the photos was meant to divert attention from a Chau campaign stumble. Lin got a court restraining order against the Chau campaign to stop it from continuing to disseminate the Social Security number of Lin's wife, which was included in a Chau mailer about tax liens.
Chau and Lin are locked in a tense, costly battle for the 49th Assembly District in the San Gabriel Valley.
-- Jean Merl
Photo: Rep. Judy Chu addressing the Democratic National Convention in Charlotte, N.C., in September. Credit: Getty Images