Even if LaFollette gave Smith the endorsement, he would have struggled with his religion, possibly more even than he actually did in 1928. In the aftermath of the Immigration Act of 1924, Smith might have done better than he actually did in the Northeast, possibly carrying New York and Connecticut as well as Massachusetts and Rhode Island, but possibly just as badly in the South and the West.
Seems about right. I would say about the same as 1928 with the exception of New York and Connecticut going to Al Smith and Calvin Coolidge picking up Alabama, Georgia, and maybe Arkansas if he plays his cards right. Not sure how the African American vote would have stacked up in a Coolidge vs. Smith race.