There isn't any "of course" about it.
The way that the American electoral politics game is played today would most likely mean that NEITHER the "Republicans" (whatever that means) NOR the "Democrats" (whatever that means) would support Ukraine IF doing so would mean that they would almost certainly NOT end up in control of Congress
NOT ONLY THAT, but BOTH the "Republicans" (whatever that means) AND the "Democrats" (whatever that means) would NOT support Ukraine IF doing so would mean that they would almost certainly end up in control of Congress.
"(for obvious reasons)" - does that mean that the Ukrainians don't have the money to pay for them? Or does it mean that the Ukrainians don't have the trained personnel required to operate them in an effective manner (and won't have them unless the US government openly trains Ukrainian soldiers)?
PS - Check the B-B4 dates on those artillery rounds. If the manufacturing date is prior to 2007, then they have passed their B-B4 date and cannot be used by the US military (absent an actual war situation in which the US is an acknowledged belligerent).
PPS - In the U.S. Army, the M113 series have long been replaced as front-line combat vehicles by the M2 and M3 Bradleys, but large numbers are still used in support roles such as armored ambulance, mortar carrier, engineer vehicle, and command vehicle. [SOURCE
] In short, they are about as close to being "military surplus" as you can get. (Mind you, well trained and highly motivated troops can get performance out of "military surplus" equipment that poorly trained and poorly motivated troops can get out of "first line" equipment. <SARC>
So maybe the US is just trying to keep the two sides even</SARC>
by giving the better soldiers equipment that isn't as good as the worse soldiers have.)