Elon Musk secretly funded a conservative political group in recent years, according to four people familiar with his donations, illustrating quiet financial support for right-wing causes even before the billionaire entrepreneur in July endorsed former U.S. President Donald Trump's bid for reelection.

Two of the people familiar with the donations said Musk's contributions to the organization, Building America's Future, had started by 2022. One of those people and a third source said the donations amounted to millions of dollars, significantly boosting a group whose advertisements and social media campaigns have criticized the Biden administration and progressive political platforms of the sort Musk himself has increasingly denounced.

It was not possible to determine a precise amount and timeline for the contributions or identify documentation linking the organization's finances to Musk. Earlier on Wednesday, The Wall Street Journal reported that Musk had financed other pro-Republican groups.