Ehhh, while it did cause episode of anti-German hysteria in US, I think that it wasn't the crucial factor in US entry. We've had this discussion like 3 or 4 years ago on this board, and the consensus was, that even if TR were President at the time being, he wouldn't have been able to actually declare war on Germany quite to popular belief and numerous ATLs. Congress was rabidly pro-neutrality, and wouldn't have approved anything like actual declaration of war. Embargo, sanctions, more loans to Entente? Sure. But entering the war at this point? No.
TR would have been forced to bide and wait for opportunity to present itself, which is by coincidence... In 1917!