Both Truman and Churchill liked Stalin. Roosevelt did not.
And Roosevelt was very left wing.
Please, using the word "like" is a bit odd...they did their best to get along with him, and so did Roosevelt, although he bitched about it a lot more. All three presidents used a lot of ink talking about Stalin and you can access the papers in their presidential libraries.
It is inaccurate to say that Truman and Churchill LIKED him when the reality is that they all decided that it was practical to cultivate the best relationship they could given the circumstances.
The most positive things Truman ever said about Stalin:
1945 diary entry in reference to possible Soviet help with Japan:
“I like Stalin,” he wrote in a July 29, 1945, letter to his wife. “He is straightforward, knows what he wants and will compromise when he can’t get it.”
He said he wanted to cooperate with U.S. in peace as we had cooperated in War but it would be harder. Said he was grossly misunderstood in U.S. and I was misunderstood in Russia. I told him that we each could help remedy that situation in our home countries and that I intended to try with all I had to do my part at home He gave me a most cordial smile and said he would do as much in Russia.
“I got very well acquainted with Joe Stalin, and I like old Joe! He is a decent fellow. But Joe is a prisoner of the Politburo,” Truman said in Oregon in 1948, referring to the Soviet Union’s policymaking body.
One could infer that Truman "liked" the fact that Stalin was very blunt and direct with his plans and goals, and did not mince words. If a pot was black, he said so.
There is indeed much to like about a leader like that but that's speaking strictly in diplomatic terms.
Diplomacy is the art and science of "liking" specific characteristics and qualities in a potential adversary in the hopes of possibly turning them into an ally.
The “Declaration by United Nations” of the three-way alliance between USA, UK and USSR on January 1, 1942 was termed a
"three-way shotgun marriage"
by no less than Truman himself.
In desperate times, the enemy of your enemy becomes your friend. During World War II, the United States, Great Britain and the Soviet Union would never have been three-way allies had they not shared a mortal enemy in Adolf Hitler.
PS: Roosevelt is only viewed as "very left wing" in today's far Right terms.
The New Deal laid the foundation for the most prosperous long term economic cycle in the history of this country, and perhaps even the world.