No way Truman would have run that year; he was burned out and just didn't want to do it anymore. But let's say he did run; he would have had the fight of his life to even get nominated.
He ran in the NH primary and lost to Kefauver by several thousand votes. It opened everyone's eyes and it showed that Truman's time was done. However if he got angry and stayed in the race it would have been very interesting. I think he could have pulled it out due to being in charge and the machine being behind him but a lot of the party could have been upset especially the southern wing and they'd pull out and do the Dixie-crats again with Richard Russell and Harry Byrd.
The race would be an uphill battle for Truman as Ike was just so popular and he wasn't. Truman would fight hard and get a break once Nixon's deal comes up but Nixon still gives the Checkers speech and shuts everyone up. Truman tries to focus on it but no one cares as Ike supported him and kept him on the ticket. The issue is blown away and he looses his opening. He continues the rail campaign like in 1948 but he's not as beloved this time and a lack of a TV advertising strategy hurt. Ike and The GOP in contrast focuses on 3 things in it's campaigning: 1. Truman's failures and issues, 2. The Corruption of his administration, and 3. How awesome Ike was.
I like Ike became a beloved jingle and Truman's policy speeches in 30 minute slots were not.
Come election day it proves to be a T-total slaughter for Ike as Truman was extremely loathed then and everyone was in love with the General.
Ike/Nixon-443 EV's
Russell/Byrd-49 EV's
Truman/Barkley-39 EV's
The split Democratic party proves disastrous for Truman and he kills his party's hopes and cements his name in history as a incumbent who refused to go and brought his party down with him. Truman is humiliated and is made a fool but he accepts the results albeit not without a grudge to Ike and their inauguration day is very hostile.
