The State Department abruptly postponed an internal forum on Cuba planned for this Friday following complaints from Republicans on Capitol Hill and conservative foreign-policy experts that it featured only Castro apologists and opponents of President Donald Trump's stricter policies toward Havana.

Originally planned as a three-hour seminar featuring lectures from some of the leading architects and proponents of President Obama's rapprochement with Cuba, the State Department postponed the event Wednesday after Sen. Marco Rubio (R., Fla.) and other Republicans on Capitol Hill questioned why it was taking place and who organized it, according to three knowledgeable sources.

White House officials also intervened late Tuesday to try to shut down the event, two sources said.

A spokeswoman for Rubio confirmed that the senator contacted top White House officials Tuesday evening and that those officials acted swiftly to prevent the event from taking place on Friday, as scheduled.

A State Department spokesperson told the Washington Free Beacon "the event in question has been postponed."

"We will seek to reschedule at a later date with a broad cross-section of outside views," the spokesperson said.

The spokesperson said the event is one of roughly a hundred "analytic exchanges" that the State Department's Bureau of Intelligence and Research, or INR, facilitates on an annual basis on "a wide variety of foreign policy and national security challenges."

"The events are intended for staff and policymakers. They are ‘off the record' and the views expressed do not reflect those of the [U.S. government]," the spokesperson said.

Critics of the seminar said the fact that it was organized and planned to take place just weeks into Secretary of State Pompeo's tenure demonstrates there is still a lack of political oversight at the State department.

Although senior political officials moved quickly to shut down the seminar once they learned about it, the sources said the fact that it was planned and scheduled to take place this Friday shows that Obama holdovers and bureaucrats are still actively working to undermine the Trump administration.

"There is already a belief on Capitol Hill that the State Department is slow-walking President Trump's rollback of Obama's rapprochement with Cuba," one source said. "This kind of thing plays into that narrative and sows more division and distrust [of the State Department] among Republicans and on the Hill."

"I'm not one to constantly reference the quote, unquote ‘deep state,' but episodes like this just lend all sorts of credence to complaints that the permanent bureaucracy is bent on undermining the president's policies—how else can you read this?" the source continued.

Sources complained that the panels represented only one side—the progressive side, broadly speaking—of the debate over Cuba.

"They had no balance—nobody to represent the other side of the debate, as if that opposition doesn't exist," one source remarked.

Another source put it more bluntly.

"This was designed to embarrass the president and Pompeo—somebody needs to be held to account," the source said. "The fact that State Department officials were advancing a program that is so slanted and completely at odds with the president's directive on Cuba, I am concerned what else they have done or what haven't they done."

An emailed invitation called the forum, titled "Cuba Under President Diaz-Canel," an analytic exchange intended for "direct-hire U.S. government employees and federal government contractors."

In underlined type, the invitation said that the "views and remarks expressed during the event are not for public attribution or dissemination."

The event was to feature opening remarks from Howard Davis, the director of INR's Office of Analysis for Western Hemisphere Affairs, according to the invite.

The INR serves as a portal for other intelligence agencies findings and is supposed to analyze that data and issue reports for State Department consumption.

A panel discussion on Cuba's current "internal leadership and political dynamics" featured lectures from William LeoGrande, an American University government professor who has studied Cuba for decades and was a top advocate for Obama's engagement policies, as well as Marguerite Jimenez of the Washington Office on Latin America, a left-leaning think tank.

Anti-Castro hardliners refer to LeoGrande as the "dean of Castro apologists in Washington." The professor also has recently harshly criticized Trump's stricter policies with Cuba, in a Huffington Post op-ed.

Jimenez, another strong advocate for rapprochement, in late March wrote an article encouraging Washington engagement with Diaz-Canel, the Castro's handpicked heir.

"All of these guys were Ben Rhodes' echo-chamber," a source remarked, referring to Obama's former deputy national security adviser who played a key role in pushing for the détente with Cuba.

Another panel was set to feature remarks from Carlos Saladrigas, one of several wealthy Cuban-American businessmen who signed a letter in 2014 asking for the historic thaw and had long pushed for ending the embargo.

Saladrigas and Phil Peters were scheduled to speak on a late afternoon panel on "economic conditions and prospects for reform."

Peters is a Republican who ran a blog called "Cuba Triangle" that supported lifting the embargo. After Obama eased travel and business restrictions, Peters formed a business consulting firm, called D17 Strategies, to advise companies doing business with the Cuban government.

The INR's role in organizing the event is particularly troubling, one source said. The office is likely in charge of providing intelligence reports on the incidents involving the sonic attacks on U.S. diplomats assigned to the embassy in Havana and whether Cuba should be designated once again as a state sponsor of terror.

The State Department still doesn't know who perpetrated the sonic attacks against nearly two dozen diplomats and their family members living in Havana. The incidents, and the Cuban government's denials that the attacks occurred, led the State Department to recall nearly all of the U.S. diplomats operating in Cuba and to expel nearly 15 Cubans from its embassy in Washington.

A State Department spokesperson defended the INR's role in organizing the forum, arguing that the "analytic exchanges" are "fully consistent with the INR mandate to conduct analytic outreach by engaging with individuals or organizations outside the [intelligence community] to explore ideas and alternative perspectives, gain insights, or generate new knowledge."