So. . . Taft is kept as VP, FDR still kicks the bucket, and Wallace delays launching nukes. An attempted land invasion in Japan leads to massive loss of life, and the war begins to lose popularity. Eventually a nuke is dropped, but it recieves more scrutiny.
Due to the changes, generals are somewhat less central figures, and smaller governement isolationists begin to gain some popularity. Wallace is renominated, though with a fight, Thurmond runs as is significantly more sucessful then OTL. Taft beats out Dewey for the nomination in 44, thanks partly to Wilkie staying alive and taking some of the votes away on the Republican left.
Taft wins, goes more isolationist. With a less sucessful rebuilding of Europe, and no EU, semi-Communist governments under the label of reformist socialism take over across western and eastern Europe. The interesting result of this is a weaker Europe, but less Soviet domination because other socialist states maintain their influence as well. Instead of a massive Soviet scary block, you see a weaker socialist alliance mostly desperate to avoid another war. This leads to a reduced fear of Communism. In the US, this means blowhards like McCarthy find other things to gripe about, domestically.
Taft is re-elected, partly because Thurmond declines to run and endorses Taft, who has been courting the south with a states rights based platform. In 52 Thurmond run for the Republican nomination against a Taft supporter, not sure who, Stasson, and maybe Dewey. Thurmond doesn't gain support outside the south, but has enough power to throw the nomination to the pro-Taft faction.