From LiberalFighter's link (really worth the read):
Tonight, I pay tribute to the liberal spirit of the people of Minnesota--in the cities, on the farms, in the forests, and in the iron country of this great State.
In this center of practical liberalism, I am proud to salute a fighting liberal--the next Senator from Minnesota, Mayor Humphrey of Minneapolis. I am also glad to greet the next Governor of Minnesota, Charles Halsted....
..Through them, I salute the liberal and progressive forces of this whole region--the forces which are once again on the march against special privilege.
The Republican Party either corrupts its liberals or it expels them. It drove out Theodore Roosevelt in 1912. It drove out fighting Bob LaFollette of Wisconsin in 1924.
It was the Democratic Party of Franklin Roosevelt, not the Republican Party, that held out the hand of welcome to Floyd B. Olson , and to that hero of progressive idealism--George Norris of Nebraska.
And those liberals who have not been driven out of the Republican Party have been changed, like Joe Ball, from fighters on the people's side to champions of reaction.
True liberalism is more than a matter of words. It demands more than sound effects. It cannot hide behind the catch phrases of the Republican candidate for President-catch phrases like "unity" and "efficiency." Unity for what cause? Efficiency for what Purpose, I wonder ?...
...Now, I call on all liberals and progressives to stand up and be counted for democracy in this great battle. I call on the old Farmer-Labor Party, the old Wisconsin Progressives, the Non-Partisan Leaguers, and the New Dealers to stand up and be counted in this fight.
I guess Truman didn't think left was irrelevant and unnecessary. So different from today's party leadership.