Wouldn't give him that much "credit." Vote fraud was not unusual in the US, especially in urban areas with their (mostly Democratic) political machines, going back to the 1800s. But LBJ's stealing the 1948 primary for US Senate in Texas by manufacturing about 200 votes in a rural county was probably the most historically significant instance of it up to that time. If not for the fraud, LBJ would have been out of Congress then and could have been gone from elective office forever. American history would probably have been vastly different.
Thanks for the ping!