1) the different constituencies of Congress and the President

the inability of anyone to speak for all Congress (or virtually even for their own party in Congress) while President speaks for "the nation"

2) the nature of elections for Congress vs. elections for the Presidency

A) Congresspersons as electoral entrepreneurs frequently disregard their political party. The dominance of nonparty sources of funding and the dominant role of constituent service lead to a lack of party loyalty and discipline.

B) the lack of presidential "coattail" effects in most elections resulting in diminished (or non-existent) sense of political debt owed to the President

3) "the growth of divided government"

Critics argue that divided government renders unworkable an already cumbersome, slow and inefficient political system. Some even argue that federal deficit can be traced to the 1980s divided government where each side "played chicken" hoping to see the other side back down! They also argue that divided government made electoral accountability difficult since voters could (and did) hold both sides responsible for deficits.

Defenders say divided government is not that bad. It tends to make government less "ambitious".

4) the inherent organizational weakness of Congress

committee and subcommittee systems, weak party discipline, weak leaders, bicameralism, congressional fragmentation

5)  different historical perspectives

Presidents have at most 8 years in office while members of Congress can serve indefinitely and generally have a longer time in office than does the President

6)  distributive tendencies of Congress v. redistributive tendencies of President

Congress tends to support policies that distribute benefits to their constituents while Presidents tend to focus on policies that redistribute benefits throughout the nation

7)  institutional jealousies and protectiveness

each institution tenaciously guards its constitutional and historical prerogatives