Primaries are being held in six states in the USA on Tuesday. Voters in California, Iowa, Montana, New Jersey, New Mexico, and South Dakota are determining the candidates who will compete in the midterm elections in November. In states other than California, candidates are being selected for both the Senate and the House of Representatives, and this week the candidates for five of the total 35 Senate seats will be finalized. One of the most notable states in the races is Iowa; incumbent Senator Joni Ernst is not running for re-election there. The majority in the Senate is held by Republicans. On the House side, Republicans have a very narrow majority, and Democrats are trying to regain control. Therefore, the outcome of the primaries is closely watched in terms of the picture that will be formed in November. One of the most comprehensive primaries for the House of Representatives is being held in California. While 52 seats are contested in the state, some of the highlighted districts in the elections are seen as highly competitive seats. It is reported that President Donald Trump has called on Republican state officials to redraw congressional maps in favor of the party. Texas is said to be the first state to respond to this call, and this process seems to have accelerated a new competition over electoral districts. It is stated that California voters have approved the updated House of Representatives map amid concerns about Trump’s redistricting move. This development shows that the struggle over electoral districts can directly affect not only the candidates but also the balance of power in Congress.