Kyrsten Sinema’s Party of One

Kyrsten Sinema was standing a few yards from the border wall with four Republican members of Congress. The men were staring balefully at a row of nearby portable toilets, wondering aloud if they could hold out for a proper bathroom on the way back to the airport. Sinema assured Representatives David Valadao of California and Tony Gonzales of Texas that they need not worry on her account.

“If you know anything about me,” she said, gesturing vaguely out into the desert, “you know that I’ll go anywhere.” The two men,...