The US isn't at war in Ukraine, we're not fighting there. Nobody who's actually anti-war looks at Russia's invasion and says "oh that's fine let it happen", everyone supports the right to defend yourself.
The US is sending crazy amounts of money over there while average Americans are seeing their living standards get worse and worse. Grassroots republicans want Ukraine to fight their own war with their own money, not keep sending money over their while Americans go hungry.
So then we're not worrying about the "anti-war" position anymore, alright.
I mean, grassroots Republicans elected Reagan who beat the Soviets and Bush who wanted to "fight them over there so we don't face them here", they're certainly comfortable with spending money on the military.
They haven't historically wanted to spend that money on welfare though, so I'm not sure that Americans are going hungry because of Ukraine.
Well, in this case the war was started by someone else, with neither aid nor encouragement by anyone American. Acting to help one of the fighting parties win doesn't seem noticeable "pro-war", AFAICT, it's just a question of how the war ends, as opposed to other possible ends of the same war.
Fund the war is an odd way to put it IMO, since the war would be there anyway… but leave that. I don't follow American politics. Do grassroots republicans oppose helping Ukraine now? I seem to remember that some months ago, a large majority of democratic voters did and a smaller majority of republican ones. How has the situation changed?