Why are the Republicans looking to have Biden pushed out of office? Some are saying he should resign; others are looking at the 24th Amendment. Why are they doing this? It seems like a dumb strategy.

I suspect it has nothing to do with Harris. Republicans are certainly aware that Biden's not going to step down. And they don't want Harris to become President.

It's about tying Democrats to Biden. Biden has terrible polling numbers and is viewed unfavorably by a majority of voters. GOP candidates were planning to tie Biden around the neck of every Democratic candidate in a contested race, and force them to defend their party's choice of nominee. They wanted those candidates to have to defend their party's choice of Biden as the nominee, to vouch for his fitness for office, to argue that he's a good choice to be President for the next four years. Because that makes the candidates look bad - you never really want to be supporting something that most voters don't like. [N.B. - the Democrats will be doing the same with Trump].

But Biden's no longer the candidate. Downballot Democrats don't have to go out and make any claims about Biden. They don't have to vouch for him any more. That leaves Republicans with one less arrow to fire at Democratic candidates - and without a shield when they're asked about their support for an elderly convict.

So, they argue that Biden should step down, so that Democrats have to defend and support Biden. It won't be as good for Republicans as if Biden were the nominee - yet another aspect of their campaign strategy wrecked by his selfless decision to withdraw. But better than nothing.