Tesla CEO Elon Musk asked the Sierra Club, an environmental advocacy group, to publicize his $6 million in anonymous donations after he received flak last week for contributing to the Republican Party, according to Bloomberg.

Musk has endured a barrage of criticism following reports that he has given $88,900 to Republicans since 2017, more than six times the amount he gave to Democrats, despite publicly identifying himself as a "political moderate."

To try and mitigate the criticism, Musk reportedly asked the Sierra Club's executive director, Michael Brune, if the group would publicize the $6 million he gave them anonymously.

Brune quickly tweeted in support of Musk from his personal account and, shortly after, the Sierra Club official account tweeted a message commending Musk's contributions.

"There have got to be better topics of debate than whether [Musk] is committed to climate action," the organization's account tweeted. "He has dedicated his career to the mission of replacing fossil fuels with clean energy & has strongly backed the Sierra Club's advocacy work. We are proud to have his support."

Sierra Club employees have criticized Brune's posts internally, saying it is antithetical to the climate group's mission to uplift a man who donates to Republicans and is reportedly anti-union, according to Bloomberg.

"I appreciate the concerns that I've seen online and in email that the tweets may be at odds with our support for workers' rights and defeating the GOP agenda across the country," Brune wrote in an email to Sierra Club staff on Tuesday, Bloomberg reported. "I don't agree, but I see the risk and understand the concerns. Musk has made unhelpful anti-union statements and Tesla's labor practices are also cause for concern, so I take your comments seriously."

Musk last year donated $39,000 to a political action committee dedicated to keeping Republican control of the House. He pointed out last week that this is a fraction of the amount he has donated to the Sierra Club.