Rep. Jeff Miller, R-Fla., will run for the Sunshine State’s open Senate seat, according to a source with knowledge of Miller’s plans. A second source said the announcement could come next week. Miller will be the third Republican to officially enter the contest to replace Sen. Marco Rubio, who is vacating the competitive seat to run for president. Miller will be the third member of Congress in the race. Florida’s Senate race is a top Democratic target as the party looks to net the five seats necessary to ensure Senate control. President Barack Obama carried the state twice. On the...