I think this is a good thought experiment for anyone to run, whatever their position, so let us explore options (actual options, not pie-in-the-sky rhetoric).
Option 1: The US explicitly supports Russian goals here.
Pros: The quickest and cheapest way to end the Ukraine war. Better relations with Russia.
Cons: A massive loss of confidence (i.e soft power) in the US amongst all existing allies worldwide. NATO almost certainly dissolves. The US probably faces sanctions from most of its major trade partners. Russia becomes significantly more powerful (do we think they'd be a trustworthy ally in the medium to long term?). Signals to other bad actors (eg. China, North Korea, Iran) that the US is totally fine with a bit of cheeky expansionism, even if the target is a nominal US ally and you're not flavor of the month. Also not exactly a popular plan with the US electorate, which would make it very difficult politically.
Conclusion: Probably not aligned to US strategic interests, or the interests of the US people. Significantly increases the possiblity of of US / China war in the Pacific, or a NATO nation / Russia conflict in Europe, or an escalation of the Isreal / Islamic Nations war. Not a good idea.
Option 2: The US absolves all responsibility, cuts all aid, does nothing.
Pros: Saves some money, Ukraine has a decent chance of winning anyway at this juncture.
Cons: The chances of Russia winning go up dramatically. A massive loss of confidence (i.e soft power) in the US amongst all existing allies worldwide. NATO possibly dissolves. Signals to other bad actors (eg. China, North Korea, Iran) that the US is totally fine with a bit of cheeky expansionism, even if the target is a nominal US ally and you're not flavor of the month. Politically divisive, but probably popular enough to be feasible politically.
Conclusion: A viable option. However, it would rather run contrary to all US activity in Europe in the past 70 years and certainly loses the US power and influence abroad. Significantly increases the possiblity of of US / China war in the Pacific, or a NATO nation / Russia conflict in Europe, or an escalation of the Isreal / Islamic Nations war. If we are to dig into the historical context, this plan hasn't gone well for the US in the past (citation: The 1920's). Probably not smart in a highly interconnected world built on international trade.
Option 3: The US continues to half-ass things as it's doing now.
Pros: Relatively low risk, relatively low cost. Ukraine probably wins, Russia is certainly degraded as a future threat. NATO partners are reassured, US foreign influence is maintained if not strengthened. Encourages other bad actors to tread carefully.
Cons: It costs money. It marginally increases the chance of further US military involvement and sours relations with Russia. The US may not do enough for Ukraine to prevail (although from what we're currently seeing, I think this is a low probability).
Conclusion: A very viable option. Seems to have popular support in the US for the most part, so politically expedient. Achieves US foreign policy goals for minimal expenditure and risk of US servicemen (although, of course not 0 expenditure).
Option 4: The US goes all in, boots on the ground, substantially increased support.
Pros: Ukraine definitely wins, Russia definitely folds, NATO is greatly reassured and US foreign policy is secured. Really, really encourages other bad actors to stay in their lane.
Cons: Hugely unpopular politically. Massively expensive, greatly increases the risk of nuclear war.
Conclusion: Probably not a good idea from a cost / benefit perspective.
Of the options presented here (things that the US can actually do), only 2 or 3 are really options.
The end goal of those options will be some kind of negotiated peace. The only power that the US has here is in dictating what the terms of that agreement look like, and what the country wants to signal to foreign allies and enemies.
Linking this back to the upcoming election, I'm reasonably confident that the Dems will continue with option 3 if they come to power. It is, after all, what they're doing now. I consider this the best option.
Donald Trump is (IMO) far more likely to lean towards option 2. That's popular with his base, it ties in with his generally isolationist foreign policy positions, it's a great political talking point to show he's done something (which continuing the current option 3 approach wouldn't be). I consider this to be an awful option for the US to take from a long term strategic perspective, but realistically doesn't constitute an existential threat to the nation.
If we're to believe that his comments about 'Ending the conflict in a day' are serious instead of just stupid bluster as per usual (for the record, I don't believe this myself), then that actually brings option 1 into play.
That's the ONLY route that the US has to end this quickly and decisively. Pressure Ukraine into folding. The US doesn't have any options to categorically force Russia to capitulate that quickly. Excepting perhaps Option 4, which realistically would be complete political suicide for whomever proposes it, and possibly comes with a nomination for the 'Stupidest Decision Ever Made By A Human' award by bringing about nuclear armageddon.
Overall conclusion: When it comes to Ukraine, I have far more confidence in Harris' administration to handle it competently that I do Trumps'.
If it's an important enough issue to outweigh all the other policies that I think the Dems will do worse is a different question...