It is clear, to anyone who really analyzes the situation, that the Presidential Succession Law of 1947 needs to be rolled back to what it was between 1886-1947.
The earlier succession law provided that the President’s cabinet members, starting with the Secretary of State, would follow the Vice President in the line of Presidential succession.
The 1947 law changed that to the Speaker of the House of Representatives and the President Pro Tempore of the Senate as ahead of the cabinet members.
That has been a mistake, as it has caused those two office holders often to be from the opposition party, as under Harry Truman 1947-1949; Dwight D. Eisenhower 1955-1961; Richard Nixon 1969-1974; Gerald Ford 1974-1977; Ronald Reagan 1987-1989 and also for the Speaker from 1981-1987; George H. W. Bush 1989-1993; Bill Clinton 1995-2001; George W.Bush 2001-2003 for the President Pro Tempore, and 2007-2009; and Barack Obama 2011-2017.
That is 38 years out of 70, and also six years for the Speaker and two years for the President Pro Tempore in addition, for a grand total of 46 of 70 years, two thirds of the time.
This has helped to promote stalemate and gridlock much too often, and has led to lack of continuity fear if a President had left office.
Luckily, that only happened twice in the first 27 years, and now it is 41 years since the last President left office early, a trend that is defying American history for turnover of the Presidency during a term, which happened seven times between 1841 and 1945!
The Secretaries of State have often been major figures, and since foreign policy is so crucial now, more than ever, the need for a Secretary of State to be second in line to be President, and a Secretary of the Treasury to be third in line, outweighs the idea of an often mediocre Congressman and a overly aged US Senator being next in line instead! And the importance of party loyalty and support of the President in office also is a major factor.