National Democrats got their preferred candidates in each of New Jersey’s House primaries on Tuesday night, but the very same voters sent a strong rebuke to Sen. Bob Menendez, who barely mustered 60 percent of the vote running against an unknown challenger. The lackluster showing by Menendez, whose federal corruption trial ended in a mistrial last year, shocked Democrats and could create a new headache for the party as they try to win back control of the Senate.