To be fair I only hear this rhetoric from the QAnon branch of the Republican party. Almost all Republican leadership strongly backs Ukraine. I'm looking at the front page of Fox News and it is coming down way harder on Putin than it is on Biden. And if Fox News is hammering anyone harder than Biden then that's really saying something.
It is possible that that'll change in the same way that "normal" Republicans adopted the positions of the insane Republicans.
All that needs to happen for Republicans to abandon Ukraine and support Putin will be Trump doing so. True to his erratic nature, he's already lurched between praising Putin and condemning the invasion, but if he "settles down" in support of Putin, Republicans will be quick to follow suit. It's also important to note here that Putin has successfully manipulated Trump into taking his side multiple times over the past several years, and I don't see why he'd have a harder time doing so in this situation. It's not like Trump gives a shit about Ukraine to begin with. I doubt he could even find it on a map.
Middle class white men have been a staple of the Republicans for decades but now that demographic is dwindling nationally. That's why they see unwhite people of other classes as a threat. That's also why they've taken to this shameless gerrymandering across the country.
In their desperation, they are romancing white supremacists, conspiracy theory freaks and the mentally enfeebled. They no longer talk about real issues, they're just frightening elderly voters with pictures of homosexuals and Hillary Clinton's face. They know that Russia will bring huge resources to the next election and they're willing to let Putin have Europe in exchange. They are traitors to their own country, they certainly don't care about Ukraine.
They know they can use bullshit to whip up the ignorant freaks into frenzy. For example:
Here is why Putin is in Ukraine.
The NAZIs are committing acts of atrocity against ethnic groups and now threatening Zelensky with assassination.