Recently ousted Veterans Affairs Secretary David Shulkin is not going quietly. First, he wrote an op-ed in the New York Times slamming the Trump administration. Then he made multiple media appearances where he defended his work at the VA and said he was unjustly undermined by others within the agency. And he continues to cause a stir by fueling the debate surrounding the circumstances of his exit — namely, did he resign or was he fired?

Shulkin, who was confirmed by the Senate in a 100-0 vote and was — before an ethics scandal — among the Trump administration’s least controversial Cabinet members, says he did not quit his job and instead was fired. The White House insists Shulkin left his job willingly in the face of the ethics scandal and dissension within his agency’s ranks.

The semantics of whether Shulkin was fired or resigned may seem petty, but the distinction could affect the process to replace him. Under the Federal Vacancies Act of 1998, the president can temporarily fill a vacancy at a federal agency if the current officeholder “dies, resigns, or is otherwise unable to perform the functions and duties of the office.” Trump said he’ll nominate White House physician Dr. Ronny Jackson to fill Shulkin’s shoes permanently and in the meantime has tapped Defense Department official Robert Wilkie as acting VA secretary. But because the federal law doesn’t specify the president’s ability to make interim appointments when he fires someone, that could eventually lead to a legal challenge.

Shulkin says he was told he was fired just hours before Trump’s tweet

President Trump announced on Twitter on the evening of Wednesday, March 28, that Shulkin was out as secretary of the VA. He said he plans to appoint Jackson to replace him permanently and would tap Wilkie as acting VA secretary in the meantime.

I am pleased to announce that I intend to nominate highly respected Admiral Ronny L. Jackson, MD, as the new Secretary of Veterans Affairs.... — Donald J. Trump (@realDonaldTrump) March 28, 2018

Shulkin has held that his ouster came largely as a surprise.

He told MSNBC he spoke with the president the day he was fired and Trump made no mention he would lose his job. On Sunday, Shulkin reiterated the point in an interview with Chuck Todd on NBC’s Meet the Press and said that when he spoke with Trump, they had set up a meeting for the next morning.

Shulkin said he found out he would be fired just hours later. “Shortly” before Trump’s tweet came out, he said, he received a call from White House Chief of Staff John Kelly letting him know. “I’ve always had a good relationship [with Trump],” Shulkin said. “Our discussions have been very focused on how we can do better, how we can do things in a better way to serve our veterans. So this was somewhat of a surprise.”

He holds he never submitted a letter of resignation. “I had no intention of giving up. There would be no reason for me to resign. I made a commitment. I took an oath,” he told Todd.

The White House says Shulkin left by choice

The White House, however, is telling a different story — that Shulkin left his job willingly amid an ethics scandal stemming from an inspector general’s report that found Shulkin inappropriately accepted Wimbledon tickets and his chief of staff misled officials about the secretary and his wife’s travel to Europe last summer. Essentially, Shulkin turned a work trip into a bit of a vacation.

The Associated Press reported that the White House circulated a three-page memo to rebut Shulkin’s public statements blaming his exit on unfair political forces and insistence that he was fired. The memo reportedly points to Shulkin’s “lies,” including statements where he minimized the inspector general’s report and made misleading statements about the matter to investigators and the media. (Vox’s Jen Kirby has a full explainer on the Shulkin scandal.)

“Secretary Shulkin resigned from his position as Secretary of the Department of Veterans Affairs,” White House spokesperson Lindsay Walters said in a statement to Politico.

Whether Shulkin was fired or resigned might matter — and it might not

Under normal circumstances, Shulkin’s deputy secretary, Tom Bowman, would have become acting VA secretary in Shulkin’s absence. But Bowman — who was, like Shulkin, appointed by Trump — is said to oppose the administration’s plan to move toward more privatized services for veterans’ health.

Wilkie, the Defense official Trump tapped as acting VA secretary instead, could serve for several months until Jackson, his permanent replacement, is confirmed by the Senate. Under the Federal Vacancies Act, Wilkie could serve for 210 days.

But there is some question as to whether the Federal Vacancies Act applies if Shulkin was, as he claims, fired. The law doesn’t explicitly state what the president’s authority is in such circumstances, whether he has the power to appoint Wilkie. So if Wilkie makes a big decision as acting VA secretary, there’s a chance an outside party could sue, arguing he doesn’t have the authority to do it and attempting to get it overturned.

“It’s an open question. There are ways to read the statute both ways,” Stephen Vladeck, a professor at the University of Texas School of Law, told Politico. “There’s reason to wonder if Congress would have wanted to give the president such broad ability to fill a vacancy he creates.”

And given the constant revolving door that is the Trump White House, what happens in this case could have ramifications for whoever Trump wants to fire next — a list speculated to include more prominent officials than Shulkin.