That's next to impossible unless they make the American people suffer tremendously as well as the rest of the world that's funding them. Ukraine has already eaten through most of their munitions (according to them). To supply them when they are eating more than can be supplied, will lead to them conserving munitions. And that will allow Russia to take the east of Ukraine with ease. West of Ukraine will probably be well armed not having wasted their supplies. But if Ukraine uses those supplies to protect the eastern front, then the west becomes defenceless. The west of Ukraine will eventually be starved from supplies due to the separatists and Russians (with it's allies) controlling the east (which has many agricultural, oil and steel production), and all they will have to encourage funding, is blackmail. If Ukraine doesn't pay their mercenaries, they will turn on Ukraine. If the US or its allies doesn't deliver on enough funding to hold the Ukrainian defence, Ukraine will release bits of its blackmail to thwart pressure on the Biden administration. Ultimate power move!