So Shaheen at +7 approval leads Sununu at +27 approval? I guess Sununu's popularity is a mile wide and an inch deep.
Popular governors running for the senate in states that are partisan against their party doesn't always work.
Indeed--see Weld vs. Kerry 1996.
Including Blackburn vs. Bredesen 2018 and Lingle vs. Hirono 2012.
New Hampshire is really not comparable in terms of partisanship to Massachusetts, Tennessee or Hawaii. A Senate seat is very much within reach for Republicans, and I think Sununu would have a great shot, though his chances may be even better in 2022 if it's a midterm under a Democratic president.
