A burst of ad spending is part of a campaign tactic in which the major parties try to boost fringe hopefuls on the other side.

Four states are holding elections on Tuesday. Election officials anticipate having results by late Tuesday or early Wednesday.

© Scott McIntyre for The New York Times

Dan Sullivan, a retired schoolteacher from tiny Petersburg, Alaska, shares a name with the incumbent senator he hopes to defeat. Is he a spoiler trying to divide the Republican vote? We traveled to Alaska to find out.

© Christopher Miller for The New York Times

An early glimpse of a pivotal Senate race, heated primaries on a newly redrawn congressional map, and a special election to replace Eric Swalwell will be in the spotlight on Tuesday.

© Associated Press

Ms. Peltola, the Democratic Senate candidate, fired a longtime senior aide and named a new campaign manager.

© Kerry Tasker/Reuters