LAS VEGAS (AP) — With control of the U.S. Senate on the line, Nevada’s protracted ballot count is grinding through a fourth day. The current Senate is evenly divided, and Nevada is one of three undetermined races that will determine which party controls the chamber. Election officials are tallying thousands of votes Friday ahead of a Saturday deadline to accept late-arriving mail ballots. Democratic Sen. Catherine Cortez Masto was running slightly behind Republican Adam Laxalt, but with the remaining ballots mainly coming from the state’s urban cores, her campaign still expressed optimism. Laxalt has predicted he’ll stay in the lead as the count drags on.