On April 12, 1945 President Franklin Roosevelt tied, placing Harry S Truman (top right) in the White House less than 90 days after having been sworn in as Vice President. As evidenced by his decisions that ultimately concluded World War II, his domestic agenda and willingness to go toe-to-toe with adversaries, Truman was a man of action - and when it came to presidential succession law, he followed through as well. Sort of.
Truman's concern about presidential succession stemmed from his own experience, particularly that the nation was at war when he took office. He was also concerned that the Presidential Succession Act of 1886 placed his Secretary of State, Edward R. Stettinius, Jr. (pictured at middle right), as next in line since the Vice Presidency was vacant. While Stettinius was considered fine as a cabinet secretary, being a heartbeat away from the presidency was just a little too close for Truman's comfort.
Truman took a two-pronged approach to the problem. The short term solution was to ask for (and get) Stettinius' resignation and replacing him with James F. Byrnes (pictured at bottom right), a man the Democrats had considered as FDR's running mate in 1944 before Roosevelt killed the idea. The long term solution was taking his former Congressional colleagues to task regarding presidential succession and disability.
The result took nearly two years, but it serves as the law under which presidential succession beyond the Vice Presidency would be handled today - the Presidential Succession Act of 1947. This new version of the law restored the Speaker of the House of Representatives and the President pro tempore of the Senate to places immediately after that of the Vice President - but in reverse order from their original, 1792 positions. The cabinet officers were then placed in order after the President pro tempore, placing the Secretary of State fourth in the line of succession, the Secretary of the Treasury fifth, and so forth.
And yet, while the 1947 law remains on the books today (albeit with modifications to add new cabinet officers), it still failed to really address the fundamental questions that impaired Vice Presidents (or others) from filling in as Acting President at a time when the nation probably would have been best served by them doing so: How is a President deemed disabled? How does he resume the powers and duties of his office once he recovers?