Martha McSally hops into a crowded field.

On Friday, Rep. Martha McSally (R-AZ), the first woman combat pilot in American history, will make a grand entrance into the race for Arizona’s open Senate seat in 2018 by flying a vintage World War II plane over the state.

A conventional conservative Republican with a few years of meaningful political experience under her belt and a great personal story, McSally is the ideal candidate to help the GOP hold on to an open seat from a retiring Republican in a state that Donald Trump won by 3.5 points. It should be an easy win; Democrats have only carried Arizona once since the death of Franklin Roosevelt. But while McSally’s flashy announcement will be hard to beat, her path to the Senate is surprisingly perilous.

The problem is Donald Trump — and not just in the sense that an unpopular incumbent president creates a less favorable political environment for basically every Republican running for anything anywhere.

Trump is at the center of tensions sweeping through the Arizona Republican Party — tensions that have led to both of the state’s current senators strongly criticizing the president. Tensions that explain why the seat is open at all, and that threaten to derail McSally’s effort to even secure the nomination. Tensions that have brought forth a strong Democratic challenger, Rep. Kyrsten Sinema, a fascinating figure in her own right, on whose shoulders Democrats’ slender but real chances of retaking the Senate majority rest.

There’s more. Arizona’s incumbent Republican governor also looks vulnerable in 2018. And the state’s not-at-all-vulnerable senior senator, John McCain, one of the truly pivotal figures of Trump’s first year in office, was diagnosed last year with a severe form of brain cancer, raising the prospect of two open Senate seats in the state Read More Here