Dara Khosrowshahi, who was brought in as Uber CEO to clean-up co-founder Travis Kalanick's mess, needs to prove the company can still innovate, early Uber investor Bradley Tusk told CNBC on Monday.

"They've lost their mojo," Tusk said on "Squawk Box" as Uber shares were falling 6% on Monday to around $37 each after the company reported a massive quarterly loss last week.

"Clearly, there's not a lot of confidence in the leadership," contended Tusk, Uber's first political strategist. "Some of what Travis represented in innovation, change and intensity is lacking at the company now, and the stock is clearly reflecting that."

Since its New York Stock Exchange debut in May, Uber has more than 10% from its initial public offering price of $45 per share.

Kalanick, a hard-driving visionary who helped start Uber in 2009 and then build into a global phenomenon, was ousted as CEO in 2017 after a series of scandals, including allegations he allowed a toxic workplace of sexual harassment and discrimination to develop. His tenure at the helm also included high-profile lawsuits, contentious personnel departures, revelations about a fake app designed to fool government regulators and a profanity-laced argument he had with an Uber driver that was caught on video.

"When Uber switched from a focus on ruthless innovation to kinder and gentler, I think that solved a lot of problems," said Tusk, referring to the carnage left behind by Kalanick. "But it seems like it might have created some new ones."

"Whether it's Dara or someone else on the team, there's got to be some more belief by the market that they're going to be able to be the first on all these things," like rides and food delivery, contended the founder and CEO of Tusk Ventures, who before going into start-up funding was New York City Mayor Mike Bloomberg's campaign manager and communications director for Democratic Sen. Chuck Schumer.

Last week on CNBC, Khosrowshahi pushed back against the notion that the company has lost its "founder mentality."

"The founder mentality, that edge, that fire, is absolutely something we want to keep going at the company," Khosrowshahi said in a "Squawk on the Street" interview Friday. "It's a big part of what made the company successful, and I absolutely think it will play a big part in making the company successful moving forward."

However, Wall Street remains skeptical after Uber on Thursday reported a per-share loss of $4.72, which was much worse than expected. Revenue of $3.17 billion also missed analyst estimates. The company blames its $5.2 billion loss during the quarter largely on stock-based compensation, the price of attracting top talent in Silicon Valley.

Uber's core ride-hailing business saw better-than-expected gross bookings for the quarter, while the newer Uber Eats unit's gross bookings fell short of forecasts.

"Fundamentally, for the company to really be profitable, it can't be just Uber Eats, it can't just be ride-share," Tusk said. "They've to be that A-to-Z for transportation. Whether you're getting yourself to A to B on a bike, scooter, or a car, bus, whether furniture being shipped on a truck, or a burrito from a messenger, they've got to be the default for all of that."

Kalanick could not be immediately reached for comment.