Here's my thoughts on this.
Canceling student debt is not necessarily a good move ahead of an election. Although many would benefit from the money, most of those are already voting for Democrats, and giving them free money would not necessarily have the same impact as the stimulus payments had previously. BUT, fighting to defend the cancelation of student debt CAN help Biden. If Republicans sue to stop the bill, and it turns into a long protracted legal fight over the cancelation of student debt, it gives Biden the edge, because it makes it seems like Republicans are just fighters and that Dems didn't actually do any harm.
I know it's weird, but I really think that the best thing Republicans can do now is to back off and let Biden forgive student debt as quickly as possible. Having actually done it will do more to harm Biden than the notion of him planning to do it.
Just my thoughts.