Challenge: Make Mitt Romney president--of The Church of Jesus Christ of Latter-day Saints...
It would need two changes. Firstly, he would have to be called to the Quorum of the twelve Apostles, probably at quite an early age, and then (at least for him to be President
now) some Apostles ahead of him in seniority would have to die earlier than OTL. Frex, our current Prophet, President Thomas S Monson, became an Apostle in 1963, when Romney was only 16, while Elder Russell M Nelson, who is next in line, was called in April 1984. So if Romney were Called to the Twelve before the latter date, he would now be one heartbeat away - and President Monson is a very frail-looking 90-year-old.
This would require Romney to be Called, at latest, within a few days of his 37th birthday. This is not impossible (President Joseph Fielding Smith joined the Qo12 aged 33), but it would be unusual these days for an Apostle to be Called before at least his mid-40s.