So, if you are looking to move large predators to North America post European colonization, it would probably be in the same interests that scimitar oryx and nilgai have been introduced to Texas and Oklahoma (although the former are not running free) - exotic hunting. I don’t think that’s a very tall order, considering that exotic prey animals have already been introduced. You might want to play with eminent domain laws and the formation of the Bureau of Land Management, here. IIRC, Thomas Jefferson had an essay against the retention of fee simple (which forms the foundation of American eminent domain law) that was presented at the First Continental Congress by his affiliates who weren’t able to convince the other attendants that a nation of freeholders who held their land in allodial title was the way to go. Perhaps have Jefferson present to make his case? You might be looking at a much more “Wild West” in such a case.
I also presented a case for how this could be done with a much earlier POD. Again guys, be creative.
@Riain, if I may point out that tigers are not as flexible in terms of their abilities to exploit habitats as jaguars, which could easily lead to a redistribution of habitats (say, jaguars abandon riparian forests where their ranges overlap with tigers). Furthermore, I specifically detailed that tigers, after the extirpation of jaguars from the American East would be a suitable addition to the riparian forests there, especially after the introduction of pigs. So, the lion is not the only animal that stands out here, and bears (even grizzlies) should not be considered serious competitors to hypercarnivores like big cats because the majority of their diets are composed of plant matter.
I also saw someone suggest the Caspian Tiger as a plains predator? Caspian Tigers were like any other tiger - a specialized riparian woodland predator. This meant that their distribution and population were always limited in their native range. They would, as tigers do, hang around rivers and lakes, where the vegetation cover is much denser and suitable to the pattern of their coat.