Mayhew is clearly incredibly knowledgeable and the premise (elected officials' primary motivation is to get re-elected) seems airtight, but I had higher for evidence for that assertion, as opposed to it being an axiom. The book is dated (the second edition is the 30-year anniversary of the 1974 first edition, and, in the forward, Mayhew declined to update it because doing so correctly would require rewriting the whole book; with that in mind, note that I read the book in 2022). It's also more theoretical and anecdotal than I'd anticipated.
It was fascinating to read about (in Chapter 1, "The Electoral Incentive") how the American Medical Association rapidly mobilized against promises to implement national healthcare, to the point of member doctors sending out mailers with their bills. This was widely seen by both parties as being successful, with multiple campaigners targeted by this approach losing their 1950 elections, and it resulted in almost nobody talking about health care by 1952.
The discussions of "credit claiming" as a vital endeavor for Congress members was interesting. In short, elected officials need to make their constituency think they have accomplished pleasing things so that the constituency thinks they will continue doing pleasing things so that the constituency will wish them to remain in office so that the constituency will vote for them so that they will stay in office (recall this is their primary motivation). Related, there is a passage in Chapter 2 ("Processes and Policies") that describes "waste" (quotes in the original) that occurs when Congress allocates a large sum to show it cares about some issue, but then has no interest or incentive to track what is done with the money.
The passage in Chapter 2 that describes how much out-of-state contributions flow to members of influential Congressional committees is depressingly unsurprising.
my favorite quote: "By the same logic, it might be advantageous for opposition marginals to try to wreck the economy; if it were done unobtrusively the voters would probably blame the president, not them."