I don't see this getting a majority of the electors for balance of power reasons.
Which of the electors who voted for Charles switches to Francis, instead of just voting for the alternative Hapsburg candidate?
Could Henry VIII of England have been the alternative Hapsburg candidate?
I don't know if Henry VIII would have been an alternate candidate to be the Holy Roman Emperor, but he would have played a role one way or another.
He was a contemporary rival of Francis I. He was an in-law to the Hapsburg's as his first wife Katherine of Aragon was the aunt of Charles I, as he a Spanish prince, later king and she a Spanish Infanta. And since Lutheranism was taking hold at this time, Henry VIII, if not for his wanting a divorce and creating the Anglican Church, for a time was a champion of the Holy Roman Empire's bid to stop the Protestant Reformation in the name of the Catholic Church.