Get breaking news alerts and special reports. The news and stories that matter, delivered weekday mornings.

Tesla CEO Elon Musk has had a high-profile presence at the White House this week.

Ever the entrepreneur, he's been busy tweeting about boring tunnels under Los Angeles, but the South African-born billionaire also seems to be busy building a bridge — reaching out to the new president after vocally criticizing candidate Donald Trump during the run-up to the election.

The unexpected about-face is perplexing some among Musk’s legions of fans, who are having a hard time reconciling Musk's outspoken advocacy for the environment with his recent coziness with a president who has declared climate change a “hoax” perpetrated by the Chinese, and is kick-starting two controversial crude oil pipelines while naming an oil baron to be his new Secretary of State.

Related: Scrutiny and Uncertainty for Trump in Silicon Valley

On Friday, President Trump announced that Musk would be part of a new manufacturing team to advise on manufacturing policy. On Monday, Musk and a handful of other business leaders had breakfast with the new president, and on Tuesday Musk delivered an even bigger surprise by declaring his support for former ExxonMobil CEO Rex Tillerson’s nomination to become the next Secretary of State.

Let our news meet your inbox. The news and stories that matters, delivered weekday mornings. This site is protected by recaptcha

Responding to an endorsement of the former ExxonMobil CEO by Britain’s The Economist, Musk wrote, “This may sound surprising coming from me, but I agree (that) Rex Tillerson has the potential to be an excellent Sec of State.”

Prodded to explain by a reporter, Musk issued a tweet declaring, "Rex is an exceptionally competent executive, understands geopolitics and knows how to win for his team. His team is now the USA."

“What did they promise you in the golden room?” tweeted befuddled Musk fans in response.

As vociferous a climate change denier as Trump has been, Musk is an unabashed environmental evangelist, explaining that preventing global warming and cleaning up the air were his prime goals for launching battery-carmaker Tesla.

Billionaire Bromance

Beyond their hefty bank accounts and predilection for espousing personal philosophies in 140-character chunks, what could the two men have in common?

Speculation has been running rampant. Musk’s true believers contend that by serving on the new president’s corporate advisory council the billionaire entrepreneur will gain leverage to change Trump’s views on the environment.

Others are more cynical, questioning whether Musk might be looking to lock down even more business for his other business ventures, such as the SpaceX rocket company, which already has billions of dollars in launch contracts from NASA. Then there’s the Boring Company, the tongue-in-cheek name Musk has coined for another project he claims he is working on, building tunnels under cities like Los Angeles to help clear up highway gridlock.

Whatever the reason, some fear there could be a backlash brewing at a time when Musk needs to count on that legion of followers.

Observers have long stressed that Tesla’s strong public following — and its high-flying stock price — are based on Musk's character and reputation. Should that now begin to tarnish and chip, it could hurt Tesla as well as the South African-born executive himself. One test will be to see if those preliminary Model 3 reservations translate into actual sales once the battery car begins to roll down the line later this year.

With alternatives like the new Chevrolet Bolt EV coming to market, once-loyal Tesla fans could display their frustration by hitting Musk and company in the pocketbook.