Trump tries to push Sen. Darline Graham across the finish line over some Republicans' objections

Fresh off the losses of three candidates he endorsed in Republican primaries, President Donald Trump faces a much higher-profile test of his political power in South Carolina.

Trump is set to hold a rally Friday night in Myrtle Beach with Sen. Darline Graham, whom he endorsed for her late brother's Senate seat and whose campaign was shaken by a recent debate when she couldn't answer a question about Taiwan and the South China Sea because she was "not that informed about national security."

"The entire world is laughing at South Carolina right now and laughing at Darline Graham Nordone," said former state Rep. Adam Morgan, a Norman supporter, using the full name for Graham that some of her critics like to invoke to distinguish her from Sen. Lindsey Graham.

"President Trump's endorsement is the most powerful endorsement in the history of American politics," White House spokeswoman Allison Schuster said in a statement. "Anyone claiming otherwise is a complete and utter fool."

Trump called at least two of her opponents that night -- Rep. Russell Fry and former Gov. Mark Sanford. Sanford remains neutral in the runoff, while one of his sons, Landon Sanford, backed Norman.

South Carolinians do not want "Queen Darline" appointed as their senator by D.C. special interests and Democrat PACs, said Republican state Rep. Steven Lynch.

Graham has argued South Carolinians are "worried about their pocketbooks more than they're worried about the South China Sea."

"Is national security important? Absolutely," she said at a Wednesday event in Florence. "Can I learn? I'm smart. Yes, I'll learn. I'll become informed. Everybody has a first day on the job. President Trump, was he a politician? Has he done a good job? Yes, he has."

At the debate, moderated by Greta Van Susteren, Graham also sparred with Norman over their records.

"Fact is, I've done more in 20 days than you have done in 20 years," Graham told Norman, a five-term congressman.

A GOP lawmaker who watched the debate described her answer on Taiwan as "eyebrow-raising" and said it "didn't inspire confidence."

"The people who were watching that are the hardcore Republicans ... And a special runoff? Those voters are the most hardcore of the hardcore," said South Carolina strategist Westfall.

"I'm sorry, but respectfully, even accounting for her being new to the job, this is embarrassing and inexcusable," wrote Kevin Roberts, head of the Heritage Foundation, in a post highlighted by Fox News.

"Can we just stop this ridiculous experiment in nepotism now???" wrote Steve Cortes.

Graham's critics also noted that she said during the debate that South Carolina has a population of 50 million people when it is actually about a tenth of that size. The moment was highlighted by her one-time rival, former Rep. Nancy Mace, who wrote, "I can't even right now with this Senate race."

Norman dismissed the charge that the race had turned silly as "silly season" -- while loaning his campaign $1.3 million on Monday after pumping $400,000 into it the prior week.

A pro-Norman super PAC, Palmetto First PAC, is running a TV ad that says Graham "inherited" the seat and asks, "What if Darline Graham had any other last name?"

The Lexington County GOP, in Graham's home county, voted to back Norman. "While I am a Trump support[er] and Lexington and SC is Trump Country ... SC voters don't want anyone to twist our arms or tell us how to vote," said county chair Weber.

Photo caption: Rep. Ralph Norman, left, and Sen. Darline Graham take part in a special GOP Senate runoff debate in Newberry, South Carolina, on August 18.