Ben Carson speaks during the CNN Republican presidential debate on Tuesday in Las Vegas. (Justin Sullivan/Getty Images)

LAS VEGAS — Before setting off on a swing of northern Nevada, former neurosurgeon Ben Carson told a room of local Republicans that if he wins the 2016 race, his presidency would probably last only one term, casting himself as a White House caretaker who would sacrifice popularity to make difficult decisions.

"If I'm successful in this endeavor to become president of the United States, it’s very likely I would be a one-term president," Carson said. "There are some tough things that need to be done."

It was one of several ominous notes in a short speech and Q&A delivered to a local party fundraiser that did not quite fill the banquet room of a Maggiano's on the Las Vegas Strip. The most ominous was a theme that Carson had used in Tuesday night's debate, a reference to the seven-year-old revelation of a document that some have held up as an example of Muslim Brotherhood infiltration in the United States.

"You know, what the Muslim Brotherhood said in the explanatory memorandum that was discovered during the Holy Land Foundation Trial was that they will take advantage of our PC attitude to get us," Carson insisted on the debate stage. "We have to be better than this. We have to be smarter than they are."

At Wednesday's event, he repeated his call, but some in the audience later admitted that they missed its significance. The Holy Land Foundation, a Texas-based Islamic charity, was designated a terrorist organization shortly after the Sept. 11, 2001, attacks. In subsequent trials, FBI investigators revealed documents and conversations among  Islamist figures in which they allegedly discussed how the cause of funneling money to Hamas was furthered by creating peaceful-seeming Muslim organizations.

The "smoking gun" memorandum referred to by Carson was found after the home of Ismail Elbarasse, an un-indicted co-conspirator, was raided. It has gained legendary status in some pockets of the right, though its link between "political correctness" and the enabling of jihad was not as explicit as Carson claimed.

"The Ikhwan must understand that their work in America is a kind of grand Jihad in eliminating and destroying the Western civilization from within and 'sabotaging' its miserable house by their hands and the hands of the believers so that it is eliminated and God's religion is made victorious over all other religions," Elbarasse wrote. "It is a Muslim's destiny to perform Jihad and work wherever he is and wherever he lands until the final hour comes."

At Wednesday's event, Carson summed that up by saying that Islamist radicals "talked in that memorandum about how it would be easy to manipulate the American populace, because they would be concerned about political correctness, and they would be so concerned about trying to protect our rights that we could come in and do what we need to do."

Carson, who has faded in early state polls but is still ahead of some "establishment" candidates, suggested that a president who took this on could save the country — perhaps at his own electoral expense.