Former Gov. Jeb Bush of Florida has resigned from each of his corporate and nonprofit board positions, an aide confirmed Thursday, the latest indication that he is moving toward starting a presidential campaign.

Mr. Bush, a Republican, gave up positions at an online education firm, his own education foundation and his post on the board of Michael R. Bloomberg’s philanthropic foundation this week, the latest nonpolitical commitments from which he has detached himself as he looks toward the 2016 race.

Last month, he severed ties with Barclays, the London-based bank where he had made more than $1 million a year as a consultant, and stepped down from the boards of two other corporations, Tenet Healthcare and Rayonier, a timberland and real estate concern.

“This is a natural next step as he turns his focus toward political activity in the new year,” said Kristy Campbell, a spokeswoman for Mr. Bush.