Well, the US could have just nuked a couple of the large urban centers in Russia and then keep moving east. Unlikely the US could have taken and controlled the USSR, but it could have pushed the Russians out of Europe. The numbers were there, especially with the liberated territories.
Tho yeah, there was absolutely no mood for more war.
US casualties were almost insignificant compared to what the Russians have lost for example. The US lost 291 thousand troops killed in the whole of WW2 including Europe and the Pacific. There were medium sized battles on the Eastern front where the Russians have lost more people in a single battle.How would you expect the US to win a war in Russia after losing so many troops fighting Hitler?
About 27 million Soviet citizens died, of that about 11.5 million soldiers. The US had a population of 135 million in 1945...it could have absorbed significantly higher losses if it wanted to.
Fact is that while we tend to have a bit of a biased perception in the US when it comes to the scale of our combat contributions, we tend to think we single handedly beat the Nazis and the Japanese when in reality our combat contributions where strategically meaningful but we were a sideshow on both fronts really, and the Soviets and the Chinese respectively did almost all the actual fighting, killing and dying.
Our biggest contribution was arming and bankrolling the allies really, the fighting...well kinda of a sideshow.