John McCain will campaign with California Senate candidate Carly Fiorina (R) on Tuesday, her campaign announced.

Fiorina was a high-profile surrogate for McCain's 2008 presidential campaign and the two have since remained allies. The Arizona senator endorsed her candidacy several months ago but this will be their first joint campaign appearance. Both Republicans are embroiled in tough primary fights.

The two will appear at an employee townhall-style event at Affinity Medical Technologies in Irvine, Calif., to talk about healthcare, jobs and the economy, according to a Fiorina campaign release.