WASHINGTON -- Sen. Rand Paul (R-Ky.) is showing signs of trying to burnish his foreign policy credentials ahead of a likely run for president in 2016, establishing himself as a leader in the debate over an authorization to fight the Islamic State and backing away from previous views that critics called too isolationist .

But Paul isn't doing all that fast enough for one key Republican donor, or for the Middle Eastern group which that donor and many other Republicans support.

The Washington Examiner reported Tuesday afternoon that GOP megadonor Foster Friess excoriated Paul earlier this month over what he said was the senator's reluctance to ramp up U.S. military involvement in the Middle East. In an email he sent to Paul on Feb. 11, after the senator had taken him to lunch on the Hill, Friess pointed specifically to the question of whether the U.S. should directly arm Kurdish forces in Iraq who are fighting the Islamic State, a group also known as ISIS.

"Please change your position. Educate your libertarian followers that the Kurds are willing to be our surrogate boots on the ground. They are loyal to us and willing to confront ISIS, where everyone else in the region doesn't have the guts to do it," Friess wrote, according to the Examiner .

"I share with you your angst of having an American killed there, but I feel exactly the same heartache if a Kurd is killed," Friess wrote. "As far as I am concerned, when a Kurd is killed, an American is killed."

Friess, a frequent donor to Christian causes, specifically mentioned the Kurds' support for Christians on the front lines of the fight against the Islamic State.

Islamic State militants have forced Christians in some parts of Iraq to convert on pain of death , and militants in Libya linked with the group recently released a video that appears to show them beheading 21 Egyptian Coptic Christians .

Meanwhile, Iraq's Kurds have garnered international renown by sheltering Christians on the run from Islamic State extremists .

Friess added insult to injury with his Feb. 11 email by copying other Republican senators on the message -- and describing to Paul their efforts to support the Kurds. The list of senators included two of Paul's likely rivals for the Republican presidential nomination in 2016 -- Sen. Lindsey Graham (R-S.C.), who Friess said was preparing to propose a $500 million package of funding to aid the Kurds, and Sen. Ted Cruz (R-Texas), whom Friess praised for following his advice and publicly endorsing weapons delivery to the Kurds (possibly a reference to this Feb. 8 "State of the Union" segment ).

Friess has already made it clear that he will be supporting former Pennsylvania Sen. Rick Santorum for the presidential nomination, as he did in 2012. Santorum slammed Paul in September , after the U.S. began its first military action against the Islamic State, for what he called Paul's inconsistency on the question of America's role in the Middle East. "Is he really trying to convince Americans that he was against U.S. intervention before he was for it?" Santorum wrote of Paul.

Aides to Paul did not immediately respond to The Huffington Post's request for comment. Friess' full letter can be read at the Washington Examiner .

The Kurds in Iraq and in Syria share an ethnic background but are divided politically. Both groups are fighting the Islamic State in their respective countries. Though U.S. cooperation with the Syrian Kurds is growing , it's not yet comparable to the long and sometimes complex relationship between Washington and the Iraqi Kurds. That relationship became even stronger last summer as the U.S. helped defend the Iraqi Kurdish capital.

The Obama administration slowly ramped up the provision of military equipment to the Iraqi Kurds during late summer and fall last year. A State Department spokeswoman told HuffPost on Tuesday that the U.S. has already begun training and arming Kurdish brigades using funds approved in recently passed defense legislation . She noted the assistance the central Iraqi government has provided the Kurds, as well as the equipment passed to them by the anti-Islamic State coalition, and said legal restrictions prevent the U.S. from selling military equipment directly to Iraq's autonomous Kurdish region. Kurdish leaders have suggested that a Republican-controlled Congress would be more willing to bypass Baghdad in order to strengthen the flow of U.S. support to them.

UPDATE: 11:55 p.m. -- Sergio Gor, communications director for Paul's campaign to be re-elected to the Senate in 2016, told The Huffington Post in a Tuesday night email that Friess' characterization of Paul's views were "inaccurate."

"Senator Rand Paul has publicly called and continues to believe in the importance of arming the Kurds," Gor wrote. "Speculation or accusations that Senator Paul is not supportive of arming the Kurdish people is false."