There is only two opponents to Ukraine aid in the current federal parliament. The neoliberal FDP who just got booted out of the government and wanted to use Ukraine aid to ransom away social security, infrastructure investments and work towards mitigating climate change, and the fascist Putin financed AfD. The FDP is Merz favorite potential next coalition partner, if they should make it to parliament again. The AfD is what Merz is working towards since three years, but cannot make a coalition yet, because he needs to work more on normalizing them first. This currently happens on local and state level.

Merz is only been "pro Ukraine" because Scholz messed up regarding Taurus missiles and because the FDP used it as ransom to ruin other aspects of the state budget. Merz focused on this message as a driving wedge in the dysfunctional, now broken coalition. There is little reason to believe, that he is genuinely caring about Ukraine, or that he would make that a deciding factor in coalition negotiations.