Former Secretary of Veterans Affairs David Shulkin was ignoring the signs of a plan to oust him until a member of his staff found a memo left on a copy machine, he told NBC News NOW on Thursday.

Shulkin, who was fired by President Donald Trump via Twitter in March, said the memo laid out a plan by a “small number of political appointees” to replace him, his deputy secretary, chief of staff and acting undersecretary, with officials more aligned with the administration’s political ideology.

“Once you're faced with a piece of paper that a staff member brings you, you can't really ignore it any further,” he said.

In his new book, “It Shouldn't Be This Hard to Serve Your Country,” Shulkin lambasts the Trump administration for a toxic culture in which political ideology threatened the quality of veteran care. He describes a culture of vindictiveness, shadow policy and personal attacks that he fears will deter others from joining public service.

“I'm worried about what public services become and whether people are going to raise their hand and be willing to come to Washington when they see people treated this way,” Shulkin said.

White House spokesperson Judd Deere dismissed Shulkin's claims.

“Because of this President’s leadership, veterans now have choice in their care, VA employees are being held accountable for poor performance, and the agency has secured $86.5 billion in funding, the largest dollar amount in its history," he said in a statement to NBC News. "While the former VA secretary chooses to profit off his time in office and share outlandish claims about his private conversations with the President, President Trump remains focused on ensuring veterans receive the care they have earned through their incredible sacrifice for our Nation.”

Shulkin was fired from his position at the same time an inspector general report alleged he inappropriately accepted Wimbledon tickets and misused taxpayer dollars. He has repeatedly affirmed that he “acted appropriately.”

Instead, the former undersecretary in charge of the veterans’ health system during the Obama administration says he clashed with the Trump administration’s views on privatization of the VA.

Last year, ProPublica reported on how a trio of wealthy men dubbed the “the Mar-a-Lago Crowd” had substantial influence over the Trump administration’s veterans policies. The House Committee on Veterans’ Affairs launched an investigation into their influence in February, which is ongoing.

In a statement, the individuals insisted that their influence on the VA was minimal and that there was never any obligation for the VA to heed their counsel.

“While we were always willing to share our thoughts, we did not make or implement any type of policy, possess any authority over agency decisions, or direct government officials to take any actions,” the statement read. NBC News has not been able to reach them for comment.

“It was clear that there were a number of messages being sent that you should get yourself politically on board or this will continue to fester and create problems,” Shulkin said. “I think, quite frankly, all this was leading towards I hope that I would walk away, that this pressure would be too much and that I would resign. And, of course, I had no intent of doing that.”

The former health care executive said he often had to combat inaccurate information that the president would get from outside sources.

“The president was getting information from outside people that directly conflicts with the people who are put in that job to give him information,” Shulkin alleged.

“I appreciated when the president would call me and say, ‘David, this is what I'm hearing. You know you know, why is this happening?’ I'd say, ‘Well, Mr. President, that's actually not what's happening. Here's the correct information,’” Shulkin said.

In discussing the current impeachment inquiry, Shulkin said it was a “sad time for our country.” He praised Lt. Col. Alexander Vindman — who told House impeachment investigators that the White House made major omissions in its log of the July call between Trump and Ukrainian President Volodymyr Zelenskiy.

“I think Alexander Vindman is a patriot and felt the duty to come and to talk about what he saw,” Shulkin said. “And I think you would hope that all Americans, particularly those in public service, would do the same thing.”