Defense Secretary Jim Mattis has withdrawn his nominee for the Pentagon's top civilian job after opposition from lawmakers concerned about her close ties to the Muslim Brotherhood.

A senior official confirmed to Fox News that Mattis pulled the nomination of former Ambassador Anne Patterson to be undersecretary of defense for policy. The move was first reported by the Washington Post.

Patterson was U.S. ambassador to Egypt between 2011 and 2013, when that country's president, Mohamed Morsi, was overthrown by the military. Critics opposed her selection by Mattis on the grounds that she was too accommodating to Morsi and the Muslim Brotherhood during her tenure in Cairo.

The Muslim Brotherhood was formed in Egypt in the 1920s with the stated goal of establishing a worldwide Islamic caliphate, or empire, ruled under Sharia law. Egypt declared it a terror group in 2013 after the government blamed it for a bombing of a police headquarters that killed 16, even though the Egyptian Muslim Brotherhood denied involvement and condemned the attack.

The Post reported that Sens. Tom Cotton, R-Ark., and Ted Cruz, R-Texas, were particularly opposed to Patterson's nomination. Both men serve on the Senate Armed Services Committee, and Cruz has recently reintroduced legislation calling on the State Department to designate the Brotherhood as a terrorist organization.

A congressional source told Fox News that Cotton's opposition was largely due to Patterson's lack of experience at the Defense Department. The source said Cotton was given no assurance that Patterson knew how to strategic defense plans that commanders would have to implement.

Patterson previously served as U.S. ambassador to Pakistan, Colombia, El Salvador and the United Nations. She recently retired after serving as the State Department's assistant secretary for near eastern affairs.

Nearly two months into the Trump administration, Mattis is the only political appointee at the Pentagon. The Post reported that the White House would announce a list of nominees for senior Defense Department positions sometime this week.

Fox News' Lucas Tomlinson and Mike Emanuel contributed to this report. The Associated Press also contributed to this report.

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