In early April, Defense Secretary Jim Mattis weighed in on President Trump's second choice for Army secretary, a Tennessee state lawmaker.

It was an important development after two months of delays. The president's first choice, a billionaire Wall Street trader, had dropped out in February after being unable to disentangle his financial interests and clear ethics hurdles.

Mattis vouched for the new candidate, Mark Green, who served as an Army special operations flight surgeon and now runs an emergency-room staffing company.

"Mark will provide strong civilian leadership, improve military readiness and support our service members, civilians and their families," Mattis said in an April 7 statement.

One month later, Green has withdrawn his nomination due to claims he is a homophobe who is hostile to transgender people and Muslims.

The allegations came from Democrats and liberal civil rights groups, but the source material was freely available on the Internet. In numerous public videos, Green can be seen addressing crowds about his opposition to gay marriage, transgender bathroom rights and teaching Islam to public school students.

All three are political landmines for the Defense Department.

The military began accepting openly gay service members in 2011 after the repeal of "Don't Ask, Don't Tell." The policy permitting service by transgender troops came less than a year ago. And the last person to hold the job of Army secretary, Eric Fanning, was the first openly gay person to have that job.

The department's sensitivities toward Islam date back to at least the beginning of the war on terrorism and include controversies from years ago over destruction of the Quran up to Trump's tangle during the campaign with the family of fallen Muslim Army Capt. Humayun Khan.

Yet Mattis was unequivocal about Green last month.

"He had my full support during the selection process, and he will have my full support during the Senate confirmation process," the defense secretary said. "I am confident of Mark's ability to effectively lead the Army."

Two Pentagon officials who spoke on condition of anonymity said Mattis appeared to have been unaware of the controversial public statements.

"The White House did the vetting," said one official, but said Green was originally recommended by Mattis largely because of his military record. Most notably, Green tended to Saddam Hussein on the night he was pulled from his "spider hole" in Iraq and spent time with the dictator, eventually writing a book titled A Night With Saddam.

As for whether Mattis knew anything about Green's public and social media comments, one official shook his head and said, "apparently not."

Green's nomination began looking like a potential misstep within days of Mattis' original April statement.

Two groups backing LBGT rights — the American Military Partner Association and Human Rights Campaign — called a news conference on April 10 to showcase video of Green, a physician, claiming most psychiatrists believe transgenderism is a disease.

An audience member at a Tea Party event in Tennessee last year asked Green how midlevel members of the military view the recent social reforms imposed on them by the Obama administration.

"You asked about how to fix it, how do we get the toothpaste back in the tube?" Green responded, then referring to Bible Scripture. "I got to tell you, it is going to start with me being the salt and the light to the people around me."

Green also joked to the crowd that maybe "if Donald Trump wins, I'll ask to be his secretary of defense."

After the nomination announcement, the Palm Center, one of the groups organizing opposition, warned that Green is a "stealth extremist" who could start a culture war in the military and attempt to bring back "Don't Ask, Don't Tell."

Concerns over Green's conservative Christian politics snowballed, eventually leading the House minority whip to call his past comments "disgusting" and Sen. John McCain to publicly admit he too had concerns. McCain is chairman of the Senate Armed Services Committee, the first stop in Green's nomination process.

For his part, Green had mostly kept a low profile. He issued a statement assuring the public that politics would not play into his work as Army secretary. Then, in a subsequent posting on Facebook, as opposition ballooned, he blamed liberals for deliberately misquoting him and targeting him for his Christian faith.

It was another unneeded distraction for an administration that is still behind on filling dozens of key positions. Mattis remains the only Trump appointee at the Pentagon out of 57 positions that must be confirmed by the Senate.

The withdrawal of Vincent Viola's nomination for Army secretary in February had already set back the process. Trump has yet to announce another Navy secretary pick after Philip Bilden, a business executive and Army veteran, also withdrew from consideration in February.

The empty seats have frustrated some in Congress and could hamper lawmakers' ability to put together a 2018 defense budget, which is already under a time crunch due to late funding of this fiscal year.

"That makes it harder for us to find somebody to talk to, to make decisions, and I continue to be concerned that without Senate-confirmed decision makers, the Pentagon tends to just march in the direction it has been marching," said Rep. Mac Thornberry, R-Texas, the House Armed Services chairman.

Thornberry has warned for months that Obama administration holdovers in the Pentagon might stand in the way of House efforts to beef up the military after years of budget constraints have left troops undertrained and equipment failing.

"That does not solve our readiness problems because for too long they said, 'What readiness problem? I don't know what you're talking about,' " he said.

Jamie McIntyre contributed to this report.