Illinois' primaries put incumbent House lawmakers at risk as they face challenges from within their own parties.
Ohio's Senate Republican primary features a showdown between endorsed candidates, setting the stage for a critical November battle.
California voters head to the polls to choose a successor to Kevin McCarthy, with contenders from both parties vying for the seat.
Illinois sees potential upsets as challengers within Democratic and Republican ranks take on incumbent House members in key districts.
Ohio and Illinois primaries highlight the intensity of intraparty competition, shaping the landscape for November's general election.
With stakes high in pivotal races, Tuesday's primaries underscore the urgency of November's looming general election.
From California to Illinois, voters face critical decisions that could influence the balance of power in Congress.