Donald Trump Jr. said Sunday that he’d “love to” make New York City great again by running for mayor — after he’s helped his old man win the White House.

Trump Jr. — who scored high marks for his stand-out appearance at the Republican National Convention last week — said he “had a good time up there” and found it “exciting to be able to have a platform like that to speak my voice.

And when asked point-blank whether he’d seek to take over City Hall, a notion first floated by pundits in The Post last week, the younger Trump said, “I never like to rule anything out.”

“As my father has always said, I want to— we always like to keep our options open,” he told CNN’s “State of the Union.”

“So if I can do that as a service to our country I’d love to do it.”

Trump Jr., 38, also didn’t rule out challenging embattled Mayor de Blasio next year, but said “right now I’m more concerned about getting my father in [the Oval Office] because I know that he will do a wonderful job with that.”

His remarks revealed considerably more interest in a political career than he expressed on Wednesday, when the father of five told a breakfast meeting sponsored by the Wall Street Journal:

“Maybe when the kids get out of school, I would consider it.”

During Trump Jr.’s Tuesday night stem-winder, veteran GOP pollster Frank Luntz polled 18 focus-group members and found that 15 wanted to see him holding elected office — with Luntz adding that “they felt his father should take lessons from him.”

Councilman Joe Borelli (R-Staten Island) on Sunday told The Post that Trump Jr. “would instantly be the leading Republican candidate” for mayor if he chose to run.

Manhattan GOP Chairwoman Adele Malpass also said that after his speech, “We were on the convention floor and people looked at each other and said, “mayor or governor?’”

Former US Sen. Al D’Amato noted that “it’s tough for a Republican to run for New York City mayor. “

“But Donald Jr.’s got the stuff to do it,” the GOP elder said.

Veteran Republican operative Roger Stone, a former advisor to Donald Trump’s presidential campaign, said the son “could be a phenomenal candidate,” but suggested he set his sights on Congress instead of becoming mayor.

“The problem is, it’s just the bluest of blue cities. Republican registration is down to 19 percent,” Stone said.

“I’d like to see him run for an office that he has a reasonable chance of winning.”

Former Republican gubernatorial candidate Carl Paladino, who’s co-chairman of Donald Trump’s New York campaign committee, called Trump Jr.’s convention speech “captivating,” and said “the young man can do anything he wants to. “

“Donald Jr.’s got all the leadership qualities to run for office. He’s a well -rounded human being,” Paladino said.

But Paladino also said he thought Trump Jr. — who is executive vice president of development and acquisitions for the Trump Organization — should spend some more time working in the private sector and wait for his kids to grow up before taking the plunge into politics.

Asked for comment on the possibility of de Blasio facing off against Trump Jr., Hizzoner’s campaign spokesman said: “It’s a free country, and assuming his dad loses it will still be in 2017.”

Additional reporting by Daniel Halper and Michael Gartland