April 11, 2013: Defense Intelligence Agency Director, Lt. Gen. Michael Flynn testifies on Capitol Hill in Washington. (AP Photo/Manuel Balce Ceneta)

President-elect Donald Trump has offered retired Lt. Gen. Michael Flynn the post of national security adviser, the Associated Press reported Thursday evening.

The AP report cited a senior Trump official, who did not say whether Flynn had accepted the job.

Flynn, who served as the director of the Defense Intelligence Agency (DIA) between 2012 and 2014, has advised Trump on national security issues for months. As national security adviser, he would work in the White House and have frequent access to the president.

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After leaving the DIA, Flynn became a virulent critic of the Obama administration and the Pentagon. He took issue with a wide range of national security policies, including the administration’s approach to fighting ISIS and, more generally, its handling of global affairs.

In recent public comments, including his fiery address at July’s Republican National Convention, Flynn has emphasized his view that the threat posed by ISIS requires a more aggressive U.S. military, as well as his belief that Washington should work more closely with Moscow.

Flynn is also a champion of renegotiating the Iran nuclear deal, another foreign policy theme Trump pushed during the campaign.

Two sources told Fox News earlier this week that Flynn was in line for the national security adviser position, which does not require confirmation by the Senate. Whoever holds it is typically shielded from congressional requests to testify or produce documents.

The sources said Flynn’s potential appointment is seen by Trump’s team as a way to tap into his national security expertise, without subjecting him to intensive questioning.

Flynn’s military experience might have made him seem like a natural choice to lead the Pentagon. But without a waiver from Congress, he is not eligible to be secretary of defense because federal law says "a person may not be appointed as secretary of defense within seven years after relief from active duty as a commissioned officer."

During the campaign, Flynn was thought of as a potential running mate for Trump. However, he appeared to fall out of favor after implying that he was pro-choice in a television interview.

Flynn told ABC’s "This Week" in July that women "have to make the decision [on abortion] because they are the ones that are going to decide to bring up that child or not." The day after the interview aired, he told Fox News that he was a "pro-life Democrat."

With his public and fervent support for Trump, highlighted by his July convention appearance, Flynn challenged the military’s apolitical traditions. He was not alone in that role. John Allen, a retired Marine general, spoke at the Democratic National Convention as a Hillary Clinton supporter. Their former colleague, retired Gen. Martin Dempsey, wrote in The Washington Post that Flynn and Allen were wrong to have participated as they did.

"The military is not a political prize," Dempsey wrote. "The American people should not wonder where their military leaders draw the line between military advice and political preference."

Flynn would not be the first retired general to be asked to serve as part of a president’s national security team. Obama appointed retired Army Gen. David Petraeus as CIA director in 2011.

Colin Powell, who had served as chairman of Joint Chiefs of Staff at the pinnacle of his Army career, became secretary of state during President George W. Bush’s first term. He also served as national security adviser to President Ronald Reagan from 1987 to 1989 while retaining his Army commission as a lieutenant general.

Retired Marine Gen. James Jones, a former commander of U.S. and NATO forces in Europe, served as Obama’s first national security adviser.

Fox News’ James Rosen and the Associated Press contributed to this report.