With Chris Christie Out, Nikki Haley Is Poised to Benefit in New Hampshire

The former New Jersey governor Chris Christie’s decision on Wednesday to drop out of the presidential race shook up a contest for the Republican nomination that had appeared to be former President Donald J. Trump’s for the taking, giving a huge shot of adrenaline to Nikki Haley just five days before ballots begin to be cast in the monthslong nomination fight.

The most obviously altered battleground is likely to be New Hampshire, where Ms. Haley, the former governor of South Carolina and Mr. Trump’s first ambassador to the United Nations, is within striking distance of the former president. Even without his endorsement, many New Hampshire voters who planned to side with Mr. Christie as an opponent of Mr. Trump’s are likely to flip to Ms. Haley, as is potentially some of Mr. Christie’s leadership team.

But the jolt will have much broader implications, argued John Sununu, a former New Hampshire senator and the brother of the current governor, Chris Sununu, both of whom have endorsed Ms. Haley. A contest that has centered on Mr. Trump’s return and the fight between Ms. Haley and Gov. Ron DeSantis of Florida for second place will now focus squarely on the threat Ms. Haley poses to Mr. Trump’s coronation.

A memo that Mr. Trump’s campaign blasted out after Christie’s announcement on Wednesday night did just that, broadcasting what it called internal polling that showed Mr. Trump beating Ms. Haley in a head-to-head contest 56 percent to 40 percent.