U.S. Sen. Lindsey Graham’s endorsement of Jeb Bush for president is designed to boost the former Florida governor’s lagging campaign by targeting veterans and military-attuned voters — key demographics in any South Carolina Republican turnout.

But the endorsement may also be the proverbial double-edged sword for Bush, as Graham remains highly popular among his supporters but loudly derided by his political foes.

The divide, which already is playing out in the S.C. GOP primary, didn’t seem to faze Bush. He readily accepted Graham’s backing Friday inside a North Charleston hotel meeting room.

“I’ll take all of his enemies because he has a lot more friends,” Bush said as he stood in front of about one dozen ex-military men from the region.

More than 385,000 veterans currently live in South Carolina.

Graham delivered his support for Bush just hours after Thursday night’s televised debate which at times featured a display of party in-fighting, particularly between front-runners Donald Trump and Sen. Ted Cruz, R-Tex. He described Bush as having the best temperament and global view needed to serve in the White House.

“I have concluded without any hesitation, without any doubt, that Jeb Bush is ready on day one to be commander-in-chief,” Graham said. “He understands that America can’t go it alone, but of all the others, he understands how to bring the world on board.”

A Graham aide said the endorsement had been in the works for just a short time. Graham ended his own bid for the White House in December, citing low poll numbers and being shut out of the top tier during candidate debates. A number of Graham backers have since jumped to the Bush column in South Carolina.

Bush also confirmed he had previously consulted with Graham on issues of national security, and that the endorsement carried implications into other primary states.

“This is a big deal nationally,” Bush said, adding that Graham “is by far and away recognized” as one of the most consistent supporters of ensuring a strong national defense.

During the press event, Graham was asked why he didn’t support fellow GOP Sen. Marco Rubio of Florida, who was recently endorsed by another Upstate Republican in Congress, U.S. Rep. Trey Gowdy, R-Spartanburg.

His answer was that Rubio is just too young.

“I think Marco Rubio will be president of the United States one day,” Graham said. “I think he’s one of the most gifted people I’ve ever met. I like him. But I wasn’t ready to be president at (age) 44.”

Of all the candidates who have visited South Carolina, Bush has made one of the more direct appeals to military aligned voters. He picked up the early support of Medal of Honor recipient James Livingston of Mount Pleasant, even recognizing the retired Marine major general from the stage Thursday.

Graham predicted that South Carolina, which votes Feb. 20, would be good to Bush as the primary duels shake out over the next three weeks.

“South Carolina is going to re-set this race,” he predicted of Bush’s chances.

Graham also continued his criticism of Trump, particularly for his call to temporarily ban Muslims from entering the U.S., something Graham said will never or could never legally happen.

“Don’t run for president if you are going to double-down on crazy,” he said.

Trump addressed the endorsement on Twitter. “Sen. Lindsey Graham embarrassed himself with his failed run for President and now further embarrasses himself with endorsement of Bush,” he wrote.

Bush took a different view. “Lindsey Graham is a patriot; he loves his country,” Bush said.

Meanwhile, the watch for endorsements from the two other high ranking South Carolina Republicans, U.S. Sen. Tim Scott and Gov. Nikki Haley, continues. Both are being closely watched and courted for an endorsement in the coming weeks.

Emma Dumain of The Post and Courier’s Washington, D.C., bureau contributed to this story. Reach Schuyler Kropf at 843-937-5551