(NewsNation) — Former President Donald Trump, who is now the oldest presidential nominee of a major political party, won’t win or lose based on his age, said New Hampshire’s Republican Governor Chris Sununu.

“The age issue has played out. Biden lost that question,” Sununu told NewsNation’s “Elizabeth Vargas Reports” on Friday.

“The issues of this campaign are absolutely going to come down to inflation, the border, the fact that people can’t pay their credit card bills,” he added.

Sununu said Republicans must concede that Vice President Kamala Harris’ “honeymoon period” will last the rest of this month. Then, he says, Republicans will force Harris to stand on her record, “which is not good.”

He said the barometer for the success of the Harris honeymoon will be evident, for better or worse, by Labor Day.

“If she’s not leading by four or five points in all the swing states by the end of August, she’s in trouble because then, it gets back to issues.”

Sununu wrote a letter to The New York Times this week, calling on his fellow Republicans to end the “trash talk” and focus on issues, but he acknowledged that Trump probably won’t heed that call.

“The former president has his style. He’s bombastic. I think it doesn’t work in many ways. It riles up his base (but) doesn’t play to the general election. (But) for all the other candidates that are trying to kinda be ‘“’Trump Light’ … stick to the issues. Republicans win when folks have to stick to the issues,” he said.

Sununu also agreed with a recent political comment by Sen. Lindsay Graham, R-S.C., who said that Democrats have a policy problem while Republicans have a personality problem. But Sununu added: Democrats won’t win on a strictly “never Trump” platform.

“’At least we’re not Trump, so vote for us’: That’s not a reason to really elect a leader of your country,” he said.