Obama would be the first major presidential candidate to drop out of the modern campaign financing system for the general election since its creation in 1976 in the post-Watergate era.
John Edwards, the former senator from North Carolina and 2004 vice-presidential nominee, was the most recent candidate to drop out of the race, having failed to score a win in any of the early contests.
There were those who hailed the announcement by initial leadership candidate Simon Thomas to drop out and throw his weight behind her as a gamechanger that would stop Leanne Wood's momentum in its tracks.