Republican Congressman Joseph Martin was the Speaker of the House of Representatives from 1947 to 1949 and from 1953 to 1955. He had an antagonistic relationship with President Truman. He is pictured here speaking to Republican Delegates before the 1968 primaries. The New York Times reported on the 168 delegates. Read more about Representative Martin on the US House of Representatives History site, on Wikipedia, or in his 1968 New York Times death notice.
Senator Robert M. La Follette Jr. of Wisconsin and Representative Almer Monroney of Oklahoma were the principle architects of the Legislative Reorganization Act of 1946. You can read more about the act on the House history site.
Truman called a special joint session of Congress to "set out a 10-point program for the welfare and benefit of this country". He bemoaned Congress' inaction on that plan in a speech in 1948, which you can read from PBS.