Curate, connect, and discover
Not to mention, you have the narrative struggle of being pulled in two different directions.
Tom Riddle, as a half blood in Slytherin, is pulled between these two extremes of the wizarding world. Abraxas being the elitist pureblood rhetoric of protecting the status quo and Leach representing the muggleborn movement for equality.
If you want to draw an even bigger connection between Leach's fall and Voldemort's rise, you could say that Tom wanted to believe that things could change. He wanted to believe Leach could do it. And when it didn't happen...well it's time for Riddle to take the reins and force the purebloods to change it themselves.
Riddle: You want to uphold the status quo? Well I'm gonna hold it up SO HIGH you'll beg for me to stop.
And they did.
I mean when you look at Voldemort's ranks it really shows just how much he's likely changed the concept of blood purity.
I mean, would post-Grindelwald purebloods be willing to work with werewolves, vampires, giants, etc? I doubt it. And then you have the half bloods who joined.
Would those post-Grindelwald wizards turn against eachother and actively torture and kill other purebloods (ex. The Longbottoms) from their already limited gene pool? I very much doubt that.
Voldemort limited the concept of blood purity to be against muggleborns and anyone who disagrees with Voldemort. And you can even argue that he would welcome muggleborns since he canonically attempted to get Lily Evan's on his side.
Riddle over here sneakily making the Death Eaters more tolerant by upholding the status quo he defined and placing all of his supporters on an equal level when it came to receiving his approval and being in danger of wizard jail.
So I suppose Riddle found a middle ground after all.
Its supremely unfair how under utilized Nobby Leach is in fanfic.
He's a blank slate! The 1st Muggleborn British Minister of Magic but we know very little about him personally or even the circumstances of his election.
Voldemort rose to power in the late 60s-early 70s. Leach was minister sometime between 1962-68. And Leach was supposedly threatened from returning to his position or possibly assassinated.
Do you think poor, working-class, assumed Mudblood of Slytherin Tom Riddle didn't see these shady dealings and go "Okay so taking the legal route to power won't work."
If having power was Tom's only goal then he absolutely would've taken a quicker route to it. But instead Nobby Leach's failure just proved the system was too broken to fix from the inside.
(Quick disclaimer, I think Riddle only used the blood-purity thing to get an in with the purebloods who were running the country. There are better posts that expand on this idea in detail so I'm not going to get into it too much here. Okay? Okay.)
We know so little about Leach that he could conceivably have gone to Hogwarts at the same time as Tom Riddle. Did they know eachother? That's up to you, but if they went to school together then they definitely knew OF eachother.
So here you have Nobby Leach who hit the ground running after graduation, who clawed his way to being the FIRST muggleborn Minister of Magic in a government made up of bloodpurists, and then he just...resigned? Fuck that. That doesn't fit at all.
And anyone with half a brain would've picked up on that. Tom Riddle could not have missed how uncharacteristic this would be if he knew Leach, or heck just noticed the sheer will and patience it takes to become THE Muggleborn Minister of Magic.
On that note, there might've been some sort of Muggleborn movement happening in the background following Grindelwald's defeat. After all it takes more than one person to achieve this kind of victory.
So Tom Riddle watches (or is apart of 👀) a fast-paced, determined movement place the FIRST Muggleborn Minister of Magic and then watches as this victory silently tumbles down into forgotten history.
Meanwhile Tom builds the Death Eaters who also work outside the system via raids and murder despite the fact that they all work inside of it already. Theres already lots to unpack with THAT decision but moving on... Once the Ministry finally gets its shit together and arrests the (clearly labeled with Dark Marks) perpetrators, throwing them in wizard prison eventually reaching the point where they would be thrown in without a trial (Sirius Black), the Pureblood lawmakers all of a sudden realize "oh fuck, this is getting real."
And now what do they have to do to avoid suspicion in this very Red Scare-esque era of spying and tattling on eachother (it worked for Karkaroff) to avoid wizard prison? Play nice with the Muggleborns.
TL;DR
Nobby Leach: went the legitimate route to making change by working WITHIN the system. He rose fast and fell silently.
Tom Riddle: went the shady route to power by working OUTSIDE the system, painstakingly working for decades to build a support base, and falling in notoriety.
There needs to be more fics with them as foils to eachother. And if it has to be me, I warn you it will take YEARS to finish.