Jackson's path differs from Donald Trump's, and the 72-year-old healthcare magnate and investor brings a vastly different persona to his first campaign. Unlike Trump, who was born to wealth, Jackson spent his early years bouncing through foster homes before launching his first company as a young man.

One of them is a Republican senator and ally of the president. The other is a retired schoolteacher whom Republicans accuse of being a Democratic plant to siphon away votes.

The letters are the latest escalation in a legal battle between California and President Donald Trump's Department of Justice, which has recently focused on the state in its efforts to root out noncitizen voting ahead of the midterm elections.