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.

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