With Travis Kalanick's resignation as chief executive of Uber, the company's board is now tasked with finding a new leader to help the company turn the page after a scandal-fueled 2017.

Mounting pressure from investors prompted Kalanick to resign Monday night, one week after he announced he would take an unspecified leave of absence from the company to grieve the unexpected loss of his mother.

Uber's board will now also be tasked with filling the company's top spot. Right now, there are no clear contenders. However, a number of high profile names have been speculated as possibilities, including recently resigned Yahoo CEO Marissa Mayer and Facebook chief operating officer Sheryl Sandberg.

But don't expect to see Sandberg, who has been a champion for women in the workplace with her "Lean In" movement, to jump ship to Uber. A source close to Sandberg told NBC News she plans to stay at Facebook, despite a New York Post report claiming she's a top choice.

Other names mentioned in the rumor mill include AOL CEO Tim Armstrong; and Helena Foulkes, executive vice president of CVS.

Related: Uber CEO Travis Kalanick Resigns After Demand from Investors

Uber has been conducting a search for a chief operating officer since Kalanick admitted earlier this year that he needs leadership help; however, recent departures have left a gaping hole in Uber's leadership team.

Uber's Chief Business Officer Emil Michael left the company last week. Uber President Jeff Jones departed earlier this year after less than one year on the job.

“I love Uber more than anything in the world and at this difficult moment in my personal life I have accepted the investors’ request to step aside so that Uber can go back to building rather than be distracted with another fight,” Kalanick said in a statement.

He will remain on the company's board of directors.

"This is a bold decision and a sign of his devotion and love for Uber,” a statement form Uber said. “By stepping away, he’s taking the time to heal from his personal tragedy while giving the company room to fully embrace this new chapter in Uber’s history. We look forward to continuing to serve with him on the board."

Uber board member and investor, Bill Gurley, tweeted about Kalanick's impact on the world.