Paul manages to win the Iowa Caucuses with a small plurality; his best performances are confined to small caucus states (Alaska, Maine, Kansas) and to states where the far-right Republican Party is strongly against Christie (Oklahoma and Louisiana). The evangelicals and SoCons who dominate the Missouri GOP feel they have no candidate who speaks for them, and a plurality of caucus-goers choose "Unpledged." Paul withdraws from the race at the end of April, allowing Christie to win the later contests like Utah and South Dakota with 70+ percent of the vote.
I honestly think a Christie-Paul race could be interesting! Rand decides to focus on winning every single caucus state and does so (Iowa, Nevada, Maine, Minnesota, Colorado, Alaska, Idaho, North Dakota, Missouri, Kansas, Guam, American Samoa, Virgin Islands, Marianas, Hawaii, Louisiana, Nebraska, Montana, Wyoming), he also creates a strong wall in the South, winning Kentucky and Texas thanks to the Paul brand name and wins neighboring states New Mexico, Oklahoma, Arkansas, Tennessee, Indiana, Virginia, West Virginia, Illinois, Indiana and Ohio.