DES MOINES, Iowa — Some Republicans are accusing the party’s neoconservative hawks of playing dirty pool in an attempt to smear Sen. Rand Paul as a bigot for having an aide who once expressed admiration for Lincoln assassin John Wilkes Booth.

The aide, Jack Hunter, who quit on Monday, was eased out by Mr. Paul after a news website revealed that, as a radio “shock jock” some years ago, Mr. Hunter advocated the Southern states secede once again from the union.

Saying he had become more libertarian and broadminded since his days as the “Southern Avenger,” Mr. Hunter revealed his resignation in a letter to the Daily Caller website.

An unusual mixture of evangelicals and libertarians claims the Hunter exposure was an attempt to discredit Mr. Paul, a freshman Kentucky Republican. They assert that the enmity of the interventionist factions in both the Republican and Democratic parties for Mr. Paul stems in part from his being the only potential 2016 GOP presidential nomination contender so far to condemn the neoconservatives for their readiness to use military force to change foreign governments, particularly those considered a threat to Israel.

Mr. Paul delayed nudging Mr. Hunter out the door for 13 days, after the July 9 story appeared in the Washington Free Beacon.

The Beacon is part of the Center for American Freedom, whose chairman, Michael Goldfarb, was once an adviser to the strongly interventionist Emergency Committee for Israel, which includes leading neocon William Kristol on its board. Some in the anti-interventionist GOP faction thinks it is significant that Beacon Editor Matthew Continetti is married to Mr. Kristol’s daughter.

“Bill Kristol, through his son-in-law, fired the first salvo in the 2016 presidential primary,” said Pastors & Pews founder David Lane, who organized a two-day meeting of evangelical ministers in Des Moines last week that featured Mr. Paul and fiery Texas Sen. Ted Cruz, considered another potential 2016 GOP nomination candidate despite his recent protestations to the contrary.

“It’s the neoconservatives’ agenda, primarily based on an imperialistic and internationalist foreign policy,” Mr. Lane said. “It doesn’t end with Rand Paul. They’ll go after any traditional conservative that gets in the way of their desire to police the world.”

Kansas GOP central committee member Charles Sciolaro, a cardiac surgeon and evangelical activist who attended the Des Moines conference, also saw neoconservative coordination at play.

“It’s the timing of the hit piece in the Beacon — out of the blue, like a missile attacking the flank, and in the middle of the [George] Zimmerman trial — and for what purpose?” Dr. Sciolaro said. “To ambush Sen. Paul’s political momentum.”

Paul in Iowa

At a private dinner after the pastors’ conference, Mr. Paul met with nearly 40 black and Hispanic evangelical ministers and business owners to learn from them, he said, how the GOP can connect on more effectively with their communities.

The assembled Hispanics told Mr. Paul just what he did not want to hear — that the key to winning over their community’s voters is for Republicans to support an eventual path to citizenship for illegal immigrants. Mr. Paul’s immigration plan provides for legalizing qualified people who had slipped across the borders but not for offering them eventual citizenship.

Mr. Paul pressed them on the question and they said it would be difficult for him to attract significant numbers of Hispanic voters if he didn’t back citizenship. He held his ground.

Nonetheless, the black and Hispanic evangelical leaders said afterward that if the Kentuckian sought the 2016 nomination, they would support him with an enthusiasm, most said, they had not been able to muster for previous GOP presidential candidates.

Mr. Paul’s 13-hour filibuster aimed at getting President Obama to rule out drone killings of U.S. citizens and his sponsorship of a federal “Life Begins at Conception” bill have won him unusual national name recognition only two years into his first Senate term.

But the issue with his aide has for the moment muddled Mr. Paul’s once-positive image.

“There are three ways to take down a political opponent — tie him to a sex scandal, attack his credentials or call him a racist,” said Dr. Sciolaro.

“Sen. Paul cannot be successfully challenged on any of the three — and is definitely not a racist,” added Dr. Sciolaro, who first met Mr. Paul in January on an eight-day trip with him to Israel, during which Mr. Paul earned positive reviews from some of the Jewish state’s most conservative religious and political leaders.

They singled out for praise what they said was Mr. Paul’s candor in saying the U.S. would defend Israel, but Israel should enhance its foreign policy independence by weaning itself from the $3.1 billion it receives annually in U.S. foreign aid. Mr. Paul has also urged an end to the $1.5 billion in annual U.S. aid to Egypt.

“In Egypt, democratic authoritarianism is replaced with military junta,” Mr. Paul said. “American neocons say send them more of your money.”

Such swipes at hawks generally make anti-interventionists beam, but Mr. Paul gave spotty performance at the libertarian FreedomFest in Las Vegas the week before his Des Moines outing.

He was a no-show at two panels on which he had been scheduled. Mr. Paul abruptly ended, after 14 minutes, a scheduled 30-minute stand-alone speech, prompting the master of ceremonies at the podium to express aloud his surprise at how short the speech turned out to be. Some younger attendees afterward said they were disappointed with Mr. Paul’s delivery, finding little to arouse or energize them. But at a major-donors’ luncheon the next day, Mr. Paul gave a more spirited — and well-received speech.

Distraction

But since July 9, the Jack Hunter issue has distracted him, causing his anger at neoconservatives to heat up. That anger, say some independent analysts, stems from the fact that party interventionists dismiss Mr. Paul as an isolationist unwilling to defend and pursue America’s vital national interests — especially in the war on radical Islamic terrorism.

“The neoconservatives, especially after 9/11, have replaced an expansionist Nazi regime of WWII and the Soviet Union with a concocted concept, often dubbed ‘Islamo-fascism’ or just ‘Islamism,’” said Robert Schadler, a foreign policy official in the Reagan and George H.R. Bush administrations. “Unlike Nazis and Soviets, Islamic terrorists and extremists are not a disciplined coherent phalanx but badly fragmented, often hating and fighting each other. Thus, it’s a problem that requires vigilance but does not constitute an equivalent threat to our very existence.”

Mr. Schadler sees Sen. Paul as seeking an alternative vision to that of former House Speaker Newt Gingrich, former Clinton White House National Security Adviser James Woolsey, Mr. Kristol and Freedom Center director David Horowitz, who tend to agree with Norman Podhoretz’ thesis in “World War IV: The Long Struggle Against Islamofascism” that this struggle may last a century and require near-constant military interventionism by the U.S.

Mr. Paul’s taking on the neoconservatives could have political consequences, given the failures of his father, former Texas Rep. Ron Paul and former Reagan White House adviser Pat Buchanan to find success with the non-interventionist issue in their GOP presidential nomination runs.

One problem, as anti-interventionists see it, is a media/think tank/party establishment deck stacked against them. From Fox News to most of the major conservative think tanks and the Republicans in Congress, the neoconservative world view has been dominant for many years in the GOP foreign policy establishment.

But Brett Schaefer, Heritage Foundation foreign policy expert, thinks that’s a misperception. “A few neoconservative Republican voices tend to dominate airtime,” said Mr. Schaefer. “Sen. John McCain, for instance, is a frequent and eager media guest.”

“The decision to attack and remove the Taliban government in Afghanistan response to the 9/11 attack was clearly consistent with conservative foreign policy, but the subsequent decision to rebuild