Elon Musk has been a fierce advocate of energy conservation, lowering carbon emissions and reducing Americans’ dependence on fossil fuels, so why is he getting close with an administration that seems to be diametrically opposed to those goals? And will it threaten the loyalty of his dedicated band of fans?

Musk’s determination to herald clean energy with his electric-car company Tesla Motors Inc. TSLA, +4.42% and solar-power firm SolarCity Corp. has won him a legion of fans who feel the same way, many of them staunch opponents of President Donald Trump. Despite publicly speaking out against Trump’s candidacy, Musk has cozied up to the new U.S. president, including a surprising endorsement Tuesday afternoon.

Also read: Elon Musk plans crazy 2017 for Tesla, but SolarCity may be biggest headache

A day after his second official meeting with Trump, Musk shocked many of his fans and followers when he publicly endorsed Rex Tillerson, Trump’s nominee for Secretary of State. Tillerson was the chairman and CEO of Exxon Mobil Corp. XOM, -1.61% for a decade before resigning at the end of last year, and basically represents Big Oil, the industry that Musk has been crusading against since becoming CEO of Tesla.

Jaws dropped in the collective Twitter-verse when Musk tweeted on Tuesday:

In response to a question from Bloomberg News reporter Dana Hull, Musk expanded, saying that he shares The Economist’s opinion that Tillerson should be given the benefit of the doubt unless his actions prove otherwise.

“Rex is an exceptionally competent executive, understands geopolitics and knows how to win for his team,” Musk tweeted in response to Hull. “His team is now the USA.”

Musk has certainly changed his tune since before the election, when he said on CNBC that “Trump is probably not the right guy” for the U.S. presidency. In mid-December, Musk and Travis Kalanick, the co-founder and CEO of Uber Technologies Inc., were named to Trump’s strategic and policy forum, to provide regular input on the economy and job creation, an irony in the case of Uber and its investments in driverless cars technology.

Uber has paid for its role in the Trump administration, with protesters showing up on Trump’s inauguration day to block access to the company’s San Francisco headquarters and promising to boycott the company’s ride-hailing service. But Musk and his companies—which also includes Space Exploration Technologies Corp., known as SpaceX—had escaped the same vitriol, despite more interactions between the two that included Musk’s appearance at a meeting with Trump and other executives on Monday.

See also: Here is why Tesla is Baird’s top stock-market pick for 2017

A backlash began to brew Tuesday, with some on Twitter challenging Musk with responses like “What did they promise you in the golden room?” and “Too bad [Tillerson’s] old team was trying to destroy Team Earth.” Musk’s environmentalist fans are unlikely to be big fans of Trump’s media clampdown on the U.S. Environmental Protection Agency, temporarily suspending all new business activities and barring any external communications activities, and an executive order to advance two controversial oil pipelines.

Musk has remained mostly silent about his reasons for continuing interaction with the Trump administration, and Tesla did not immediately respond to a request for comment on this story. Is Musk simply trying to get cozy with Trump and Big Oil so that he can influence the administration’s environmental agenda? Or is Musk just focused on his own power and allies, such as fellow PayPal founder Peter Thiel? CNBC pointed out Tuesday that Musk could be a winner under Trump, as Thiel pushes for commercial space companies to have more of a voice with the NASA transition team.

Musk counts on his die-hard fans as customers as well as investors, and their belief in him helped Musk win shareholders’ support for Tesla’s acquisition of SolarCity. If Musk alienates them, it could hurt Tesla in a very important year for the company, which would be tough to offset with whatever gains SpaceX could get from a close relationship with the president.