Tuesday's primaries and a special election to fill an open congressional seat will be the best sign yet of how the political balance of power could change in November's midterm elections.
To see what's at stake, check out this interactive slide that breaks down which seats may be up for grabs this fall.
Anderson Cooper goes beyond the headlines to tell stories from many points of view, so you can make up your own mind about the news. Tune in weeknights at 8 and 10 ET on CNN.
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