Reuters reports that Facebook founder and CEO Mark Zuckerberg’s lobbying group, FWD.us, has lost a key member: Billionaire environmentalist Elon Musk. Though a Tesla spokeswoman told Reuters that Musk wasn’t willing to explain his decision to jump ship on FWD.us, the billionaire reportedly took issue with the lobbying group’s support for several senators, including one who is pushing for the Keystone XL pipeline and another for oil drilling in Alaska.

FWD.us’ website says the lobby group is an organization founded by key leaders in the tech community to support policies that keep the U.S. and its citizens competitive in a global economy. The group focuses on immigration reform and education reform.

In a statement obtained by Reuters, FWD.us spokeswoman Kate Hansen said that group is very appreciative of the “continued support” of their founders and contributors even though “not everyone will always agree with…our strategy.”

This isn’t the first time this week that Zuckerberg’s political group has dealt with controversy. The Washington Post reported Tuesday that several liberal organizations have launched a boycott of Facebook because of FWD.us’ funding of ads for senators who support immigration reform. The Post says that ads champion the pro-immigration reform senators’ conservative credentials by describing their support for the Keystone XL pipeline and other conservative platforms.

Progressives United, which has promised to boycott the social media network, released a statement explaining its position on FWD.us’ ad campaign.

“Leaders in the technology community have every right to talk about how immigration reform will benefit their businesses,” said former Senator Russ Feingold, the founder of Progressives United. “But instead, FWD.us has chosen a strategy that’s condescending to voters and counterproductive to the cause of reform.”

Though FWD.us may have lost Musk, the lobby group still has a powerful circle of tech leaders, including Microsoft Chairman Bill Gates and Founders Fund Managing Partner Sean Parker. The group’s contributors include Microsoft CEO Steve Ballmer, Netflix founder Reed Hastings and Group co-founder Andrew Mason.

According to Reuters, FWD.us took Musk’s name off its website on Friday after Reuters quizzed the group on the billionaire’s departure. Reuters also points out that the total amount that Musk had donated during his time with the group remains “unclear.”

David Sacks, founder of Yammer, also reportedly left the group on Friday.

Did Musk jump ship because of FWD.us’ ad campaign for senators support oil drilling or is there another reason behind the billionaire’s departure from the Facebook founder’s political group? Will FWD.us lose any more supporters in the coming weeks? Share your thoughts in the comments section.