Change/swap horses in midstream

This expression is usually used in the negative i.e. don’t change horses in midstream and is a warning not to alter one’s tactics while in the middle of an operation or project. The general consensus is that its figurative use was popularised but not coined by Abraham Lincoln in an 1864 speech in reply to the National Union League who wanted him to be their presidential candidate. Lincoln declined saying, “It is not best to swap horses while crossing the river.” Earlier citations have been found for it in American journals, one dating from 1840, so it is probably American in origin but is now used in English throughout the world. Some sources maintain it was a saying that originated amongst American settlers in the 1700s but no citations as early as this have been found to date. Before its figurative use, someone must have literally tried to change horses in midstream with presumably adverse consequences, but who this was or when it happened remains unknown.