Note: some of these things only apply to incumbents, while some only apply to challengers.
* political positions on issues, as advertised and/or as perceived by people
** how easily said perception can be changed (versus how cemented it already is)
* actual political positions as based on voting records, and whether this is different from the above
* fit to the district based on perceived ideology
* fit to the district based on actual ideology
* constituent services (can seriously make up for bad fits)
* backbencher versus leader
* teflon-coated-ness versus controversy generation (also known as gaffe/misbehavior probability)
* campaigning style–what is it suitable for (liberals, moderates, conservatives, liberal Democrats, liberal Republicans, conservative Democrats, conservative Republicans, rural voters, suburban voters, urban voters, Blacks, Hispanics, Asians, Whites, etc.)
* campaigning effort and effectiveness (some people are just lazy campaigners or haven’t adapted well to a new district’s style or such)
* charisma
* length of incumbency
* vote percentages in previous elections
* previous positions held, victories, and losses
* scandals (current and past)
* anything that dirty tactics can target (shouldn’t be a deciding factor, but should be paid attention to be ready to defend against)
* fundraising capability and fund availability
* fund usage capability (campaign on a dime?)
Anything else?
And is there a way we can distill this? Though I’m sure some professional strategists already have some sort of abbreviated list that they use in their line of work.