The White House confirmed Monday that Obama adviser Ben Rhodes will not be allowed to testify before House lawmakers on the Iran nuclear deal, after a last-ditch attempt by Republican Rep. Jason Chaffetz to pry the controversial aide loose for the hearing.

Chaffetz and the White House have been engaged in an escalating feud, all on the heels of a New York Times Magazine piece where Rhodes was quoted boasting about the administration’s success in crafting a public narrative for the Iran deal. The profile on Rhodes quotes him saying they built an “echo chamber” of experts who sold that narrative to young, often inexperienced reporters.

Chaffetz, R-Utah, chairman of the House Oversight Committee, wanted the deputy national security adviser to testify at a hearing set for Tuesday titled, “White House narratives on the Iran Nuclear Deal.”

“We’re planning as if he is attending, and he’ll have a comfortable seat awaiting his arrival,” Chaffetz said Monday afternoon of Rhodes.

But W. Neil Eggleston, White House counsel, sent a letter to Chaffetz late Monday saying Rhodes would not attend.

He cited what appeared to be an executive privilege-related claim, asserting that such a senior presidential adviser’s appearance “threatens the independence and autonomy of the President, as well as his ability to receive candid advice and counsel.” For those reasons, he said, “we will not make Mr. Rhodes available to testify.”

Chaffetz earlier had made a last-ditch attempt to pressure Rhodes into appearing. After White House Press Secretary Josh Earnest initially said he should invite GOP Sen. Tom Cotton, whom he accuses of spreading false information about the deal, Chaffetz did exactly that -- inviting Cotton to testify, on condition that Rhodes appeared as well.

“[Earnest] suggested that you should be invited to appear at the hearing as well, because you have some 'interesting insight' into the JCPOA [the Iran deal]. Therefore your appearance before the Committee would be contingent on Mr. Rhodes’ appearance at that hearing,” Chaffetz said in a letter Friday.

Asked earlier Monday about the possibility of a Rhodes appearance, Earnest did not rule it out but expressed what he called "thinly veiled skepticism about the whole exercise" and reiterated his claim that it is Republicans who should answer "for saying a lot of things about the Iran deal that turned out not to be true."

The letter from Eggleston later made clear Rhodes would not attend. Though Eggleston cited an executive privilege claim, Earnest told Fox News just four days earlier that “this has nothing to do with executive privilege.”

Sources tell Fox News that the committee was keen for Rhodes to appear voluntarily so they avoid the territory of a possible subpoena.

The magazine article that touched off the controversy outlined how Rhodes created a narrative of the deal coming out of the 2013 election of “moderate” Iranian President Hassan Rouhani and Iran’s subsequent “openness” and willingness to negotiate.

In fact, the story stated, the majority of the deal was hammered out in 2012, well before Rouhani’s election. However, the Rhodes narrative was politically useful to the administration as it presented them as reaching out to the moderates who wanted peace.

Fox News’ James Rosen and Chad Pergram contributed to this report.