In an email yesterday to the Washington Post, an aide said Bush, 61, also has ended his role as a paid adviser to a for-profit education company, Academic Partnerships, that sells online courses to public university students in exchange for a share of their tuition payments.
The aide told The Post yesterday that resignations were made "effective today."
The former governor in recent days has been ending business and professional affiliations, including some that could prove politically compromising, as he lays the groundwork for a possible presidential candidacy.
"This is a natural next step that will allow him to focus his time on gauging interest for a potential run."
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Bush on December 16 announced he was laying the foundation for a White House run, making him the first serious Republican contender in the race.
He recently ended a consulting deal with Barclays, the British investment-banking conglomerate, that paid him more than USD 1 million a year, according to reports.
The scion of one of America's most prominent political families, Jeb Bush is the son to one former US president, George HW Bush, and brother to another, George W Bush.