His 36.5 million followers grew even more curious about the phrase's meaning after presidential adviser and first daughter Ivanka Trump replied to the May 17 tweet saying, "Taken!"
Musk's tweet came after the engineer made statements on- and offline about his support for plans to start reopening the country amid the coronavirus pandemic and help get Americans back to work, thus aligning his stance with that of President Trump's.
But despite his cryptic tweet, it is unclear whether Musk would label himself as a Republican; in the past, the billionaire has described himself as an "independent" and "half Democrat, half Republican."
"I am somewhere in the middle," Musk said at a 2011 tech conference hosted by The Atlantic and UC San Diego. "Socially liberal and fiscally conservative."
In a 2013 interview with the Huffington Post, Musk said he donates heavily to both Democrats and Republicans.
"In order to have your voice be heard in Washington, you have to make some little contribution," Musk told the outlet. "But I have found Washington to be really — I guess it depends on what your benchmark is — but I haven’t found Washington to be as corrupt as a lot of people think it is, meaning it’s not as coin-operated as some people may assume, and I’m very, actually, grateful for that, because if it were, we would have zero chance."
In a more recent 2018 tweet, Musk said he is a registered independent.
"To be clear, I am not a conservative. Am registered independent & politically moderate. Doesn’t mean I’m moderate about all issues. Humanitarian issues are extremely important to me & I don’t understand why they are not important to everyone," Musk wrote.