Rand Paul
© Chip Somodevilla/Getty ImagesSen. Rand Paul has been among the most prominent voices warning against war with Iran
Over a round of golf this past weekend, Sen. Rand Paul asked President Donald Trump's blessing for a sensitive diplomatic mission.

Paul proposed sitting down with Iranian Foreign Minister Javad Zarif to extend a fresh olive branch on the president's behalf, according to four U.S. officials. The aim: to reduce tensions between the two countries. Trump signed off on the idea.

With Zarif in New York City this week for U.N. meetings and private sitdowns with journalists and think-tank experts, the prospect of the dovish Kentucky senator serving as the administration's chief diplomatic emissary has rankled many administration officials, who are expressing concern that Paul's intervention threatens to scuttle the president's "maximum pressure" campaign against Tehran.

It is unclear whether the senator will meet with Zarif. He and his office declined multiple requests for comment. But the president's willingness to tap Paul as the go-between with a top Iranian official is a demonstration both of his unorthodox approach to foreign affairs and his continuing desire, even as his aides threaten to squeeze Iran until it capitulates to U.S. demands, to entice the Islamic Republic's leaders to the negotiating table.

Trump has been attempting to start negotiations with Iran for months, a campaign that has included letters to Supreme Leader Ayatollah Ali Khamenei, an attempt to use Japanese Prime Minister Shinzo Abe as an emissary to Tehran, and public comments expressing his desire to talk. Some Iranian officials have said that they are open to negotiations, but only after the administration removes sanctions. Khamenei, however, has likened talking with the U.S. to drinking "poison."

Paul, along with Sens. Lindsey Graham (R-S.C.) and David Perdue (R-Ga.), played a round of golf with the president on Saturday at his club in Sterling, Va.

The libertarian-leaning Paul has long been wary of U.S. foreign intervention, and he's clashed with Trump administration officials over the possibility of a military conflict with Iran. When Trump last month called off retaliatory military strikes against Iran after an Iranian military official downed a U.S. drone over international waters, Paul went on the president's favorite television network to offer unqualified praise. "It really takes a statesman to show restraint amidst a chorus of voices for war," Paul told Fox News' Martha MacCallum.

He also criticized the administration's policy, arguing that Iranians view the punishing sanctions imposed by the Trump administration as "an act of war."

Paul has long been at odds with the team of hawks serving at the top echelons of the Trump administration, including National Security Adviser John Bolton and Secretary of State Mike Pompeo. At the outset of the administration, he led a public campaign against the administration's current special envoy to Venezuela, Elliott Abrams, when his name was floated as a candidate for deputy secretary of state โ€” and helped to scuttle his candidacy by bashing his hawkish views in an appearance on Tucker Carlson's Fox News show, according to a source directly familiar with the events.

Earlier this year, Paul pressed Pompeo on whether the administration believes it has the authority to battle the Iranian regime under a 2001 law that allowed the U.S. to pursue the fight against al Qaeda and affiliated terrorist groups in Afghanistan and beyond.

When Pompeo tried to sidestep the question, Paul warned the administration not to pursue such a conflict, at least not without Congress' imprimatur.

"You do not have the permission of Congress to go to war with Iran," Paul told Pompeo during the April hearing on Capitol Hill. "Only Congress can declare war."

The move smacks of desperation, said Mark Dubowitz, head of the hawkish Foundation for Defense of Democracies, which has pushed for a hard line on Iran.

"It's a fine idea to make it clear you're interested in negotiating and a diplomatic path, but you have to be selective and circumspect," Dubowitz said. "Right now, Trump has tapped everybody and their mother to be an emissary."

"The one thing that these guys don't understand is the more desperate they look for a deal the more the Iranian regime will play hard to get," he added. "Then when it comes to the table it will be even more inflexible in its negotiating position. And the final result will end up looking like Obama 2.0."

When told that the president had blessed an outsider to reach out to Zarif, a Trump administration official familiar with Iran issues laughed and quipped: "He's given up on all of us!"

Iranian officials did not reply to requests for comment.