“One of this year’s biggest primary elections is underway in Michigan, where two Democratic Senate candidates with deep policy disagreements are facing off in a major test of the party’s direction,” the New York Times reports.“The bitter, expensive race pits Dr. Abdul El-Sayed, a progressive former public health official, against Representative Haley Stevens, a centrist supported by party leaders. The winner will defend the seat of Senator Gary Peters, a Democrat who is retiring, in a battleground state that could determine control of the Senate. Along with Michigan, four other states are holding primaries on Tuesday: Kansas, Virginia, Washington and Missouri.”CNN: What to watch in Michigan’s Democratic Senate showdown and other key races in Tuesday’s primaries.