Pappas-Sununu showdown set in Democrats’ must-win Senate race: 3 takeaways from New Hampshire 

Rep. Chris Pappas (D) and former Sen. John E. Sununu (R) are poised to face off in November for New Hampshire’s open Senate seat — one of the GOP’s best pickup opportunities as they look to hold onto the upper chamber.  Pappas and Sununu, the favorites in their respective primaries, defeated a handful of challengers Tuesday. While New Hampshire hasn’t elected a Republican to the Senate since 2010, Granite…