California Congresswoman Doris Matsui’s campaign website has a press release boosting one of her Republican opponents. See this Sacramento Bee story. Matsui has a strong Democratic opponent, Sacramento city councilmember Mai Wang. There are four Democrats and two Republicans running in the primary in the Seventh District. The story says that Matsui hopes to boost a Republican so that he, not Wang, will place second and be her opponent in the November election. This is another example of how the top-two system motivates candidates to make insincere statements to manipulate who places second.
Here is the part of the Matsui campaign website that boosts one of her Republican opponents. As the Sacramento Bee points out, this Republican has not reported any campaign contributions, nor did he put a campaign statement in the Voters Guide.