As far as I know, Truman never ran against Ike.
But then, what do I know?
Sorry, Adlai Stevenson.
Of course you could still have answered the question anyway, are you claiming that Ronald Reagan endorsed Eisenhower because he was more liberal? Do you prefer Stevenson?
Since you asked me, I will tell you that you don’t know much, as you always gravitate to the most liberal option available.