• White House communications director Alyssa Farah is resigning.
• In a resignation letter obtained by CNBC, Farah said she "will be leaving the White House to pursue new opportunities."
• While Farah's exit hints at an understanding that the Trump administration will soon come to an end, the president has remained publicly defiant and is refusing to concede to Joe Biden.

White House communications director Alyssa Farah is resigning, a sign of acknowledgment among Trump administration officials, if not President Donald Trump himself, that Joe Biden's incoming administration will soon take charge.

In a resignation letter obtained Thursday by CNBC, Farah said she "will be leaving the White House to pursue new opportunities."

Farah's letter, first reported by The Washington Post, called her tenure in the administration "the honor of a lifetime."

Farah, 31, has worn multiple hats in the Trump administration. She worked for Vice President Mike Pence starting in 2017. Two years later, Farah transitioned to the role of press secretary for the Department of Defense, becoming the youngest-ever spokeswoman for the Pentagon. In April of 2020, Farah returned to the White House as director of strategic communications.

Before joining the Trump administration, Farah had worked in conservative political circles, including as press secretary for then-Rep. Mark Meadows, R-N.C., who is now Trump's chief of staff.

The Washington Post reported that Farah's last day is Friday. She aims to launch a consulting firm with a focus on defense, corporate and political issues, according to the newspaper.

Farah did not immediately respond to CNBC's requests for additional comment on her departure.

While Farah's exit hints at an understanding that the Trump administration will soon come to an end, the president has remained publicly defiant and is refusing to concede to Biden.

Trump instead is spreading false claims about voter and election fraud and is falsely insisting he won the race, while his campaign launches waves of lawsuits that have so far failed to make meaningful progress toward the goal of overturning Biden's win.

The Trump administration has granted Biden's team access to federal funds for the presidential transition, and the president-elect has begun rolling out his slate of top Cabinet picks.

Biden's team has placed heavy emphasis on tackling the coronavirus pandemic, which has killed more than 270,000 people in the U.S. and has infected 14 million. Trump, in the weeks that have passed since the Nov. 3 election, has focused little on the devastating death toll but has at times touted recent progress being made among Covid-19 vaccine candidates.

Farah in her resignation letter says, "I'm honored to have worked with the entire team on Operation Warp [Speed] who helped usher in a safe and effective COVID-19 vaccine in record time that will save countless thousands of lives."

"I'm forever grateful to have had the opportunity to serve my country," Farah said.