Dr. Ronny Jackson, President Donald Trump's embattled pick for Veterans Affairs secretary, withdrew his nomination after several allegations emerged about his conduct.

Jackson denied the allegations, which included accusations that he drank on the job and improperly gave out prescription medication. He said he was pulling out because the matter has become a distraction for the president.

"The allegations against me are completely false and fabricated," Jackson, a rear admiral, wrote in a statement released early Thursday. "If they had any merit, I would not have been selected, promoted and entrusted to serve in such a sensitive and important role as physician to three presidents over the past 12 years."

Despite his withdrawal to head the largest Cabinet department outside of the Pentagon, Jackson remains at the White House.

"Admiral Jackson is a doctor in the United States Navy assigned to the White House and is here at work today," spokeswoman Sarah Huckabee Sanders said in a statement.

Jackson also served under Presidents George W. Bush and Barack Obama.

Trump himself vigorously defended Jackson on Thursday morning. Speaking to "Fox and Friends," Trump said "there's no proof" of the allegations. The president also targeted political opponents over the Jackson controversy.

"They're trying to destroy a man," the president said. "I think Jon Tester has to have a big price to pay in Montana."

Tester, the Democratic senator who raised the concerns about Jackson, faces a tough re-election contest this year in Montana, a state Trump won easily in 2016.