Nikki Haley won the backing of New Hampshire's GOP governor. It's a key advantage she just won't have again for a long time.

• Chris Sununu's endorsement of Nikki Haley seemingly boosted her in NH despite her loss to Trump in the state's primary.
• But going forward, she'll need more institutional support to remain viable as a candidate.
• The S.C. primary will be a key test, but Haley will also need backing from Republicans in Super Tuesday states.

When New Hampshire Gov. Chris Sununu threw his support behind former UN ambassador Nikki Haley's presidential bid last month, it was a huge coup for her campaign.