The Campaign Trail really is the best presidential campaign simulator available. The choices you make seem real, imply tradeoffs and dynamically affect the story and events of the campaign. It satisfies the deep itch that players like us want: role-playing, as opposed to dressed-up spreadsheets and mathematic resource-management that underly games like President Infinity.
This actually hits the nail on the head with PI; I've only ever had one game where I felt a genuine challenge (was Guilani running in 08 against Obama and I must have dumped about £70 million into NY only to lose it by 1% while narrowly losing Virginia & Michigan)
The game eventually becomes stale; even as a low ranking candidate you just camp out in Iowa and watch yourself climb before getting a boost before Super Tuesday. The AI spends money at a stupid rate so you always end up facing bankrupted opponents
I think the problem with President Infinity is more fundamental than that. Within the current game dynamic, it's at least possible the AI could be modded/improved or buffed in such a way to make the game more challenging.
However, I think the real reason the game goes stale rather quickly is because leaking a "Power 9" scandal, trumping in a debate, or getting the "Big Mo"
is stale when there's no narrative or backstory to accompany it. What gives IRL presidential campaigns their rhythm and drama are the personalities that inhabit them. PI ignores this factor by making all candidates and campaigns fundamentally the same. While different campaigns may have different issues and candidates different characteristics, these dynamics work by simply lying "on top" of the game's base simulation rather than being employed as a way to generate the plot.
The contrast offered by the Campaign Trail is night-and-day. In a fundamental break from PI and the rest of the campaign management genre, there're no resources (command points, stamina, campaign cash, etc.) to manage. Instead, the march to election day is conceptualized as a series of mutually-exclusive decisions dynamically presented to the player as the game progresses. The result is simply genius because it achieves something other campaign management games have not: a genuine sense of role-playing for the player that allows him to engross himself in narrative scenarios like "what if JFK had run as a champion of civil rights? Jimmy Carter as an ideological liberal? or Gore had campaigned with Clinton?" That sense of alternate history is always what players of these games have longed for. The tradeoff for this type of game is a small number of scenarios and limited replayability, but the game designer was smart to inject some amount of randomness into the design so that the results never seem too pre-cooked.