Uber has to find a new CEO — Here are 8 likely candidates

Uber was already in the hunt for a high-caliber executive to help revamp the company.

Now, though, that person will get to call themselves CEO.

The ride-hailing company's former chief executive, Travis Kalanick, resigned the post on Tuesday after getting a letter from investors demanding his departure. At the time he received the letter, he was in Chicago to interview a candidate to be Uber's chief operating officer. Up until Kalanick's resignation, filling that position was the company's top priority.

Now, Uber's board is putting on hold the search for a partner for Kalanick, to start looking for a leader for the new Uber. (Kalanick, though, will have a role in finding his replacement.)

It won't be easy to find an exec willing to take on turning around the embattled company, but here's a list of some of the likely candidates for the job:

The wild cards

There are real possibilities and then there's wishful thinking. But this is Uber, the word's most valuable private company, so anything could happen.

Among the long-shot names that have been tossed around are:

• Sheryl Sandberg: Arianna Huffington was pushing for Facebook's COO to become Uber's next leader, according to the New York Post. But Recode's Kara Swisher said Sandberg won't leave the social media giant. Sandberg's name has been bandied about from the beginning, but largely as a model for the executive Uber would like to hire.

• Barack Obama: Obama's the only person on this list to have had a job that's harder than turning around Uber, so some people think the former president would be a great fit to be the ride-hailing company's CEO. It's a stretch, but weirder things have happened.

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SEE ALSO: Uber's absent leadership: The $69 billion startup needs a lot more top executives than just a new CEO