Republicans and Democrats are accusing one another of deploying underhanded tactics ahead of the 2026 US midterms, including interference in rival primaries, disguised political spending and exploitation of filing deadlines, in a bid to shape which candidates reach the ballot. The manoeuvring is concentrated in several pivotal races that could determine control of Congress, raising concerns that outcomes may hinge on tactical trickery rather than voters' genuine preferences, further undermining public confidence in the electoral process.

In Alaska's toss-up Senate race, incumbent Republican Dan S. Sullivan faces a challenge from a second candidate also named Dan Sullivan, whom Republicans allege is deliberately running to confuse voters and benefit Democratic nominee Mary Peltola under the state's ranked-choice system; the challenger denies this, and he is now under investigation by the Justice Department and Alaska election officials. In Texas, the National Republican Senatorial Committee reportedly worked covertly to encourage Democratic Representative Jasmine Crockett into the Senate primary against James Talarico, allegedly boosting her profile through favourable polling and seemingly critical ads that actually highlighted popular progressive positions, in what one source called an "AstroTurf recruitment process."