Truman was a fine man, but he could do nothing to defend his party from all the infiltrating Communists.
Most of the politicos in DC hated Truman.
He and a friend went on a tour of the nation, prior to being President, where they visited Government funded projects to root out corruption. With no notice, in a personal vehicle, and no one knew who they were anyway.
They found tons of corruption and saved the taxpayers millions of dollars. The politicos in DC hated Truman. For about the same reasons the politicos in DC hate Trump.