(CNN) - It's a tight race in Indiana, but it remains to be seen if Tuesday's primary will break the record for the closest presidential primary in American history
CNN Polling Director Keating Holland reports that title belongs to the 1936 South Dakota Republican primary when Kansas Gov. Alf Landon, the eventual GOP nominee, beat Idaho Sen. William Borah by 257 votes.
The full results:
Landon - 44,518 votes - 50.14%
Borah - 44,261 votes - 49.86%