Senator Jeff Sessions was the first senator to endorse Donald Trump, back on Feb. 28. Even earlier, in August 2015, he appeared at a Trump rally in Alabama and wore a “Make American Great Again” baseball hat. Sessions, like Trump, has advocated restrictive immigration laws, more deportations and stronger enforcement; he has been the Senate’s leader on that side of the issue. But in temperament and on many cultural issues they are not a particularly good fit.