Complex sentence: Public school entities are chiefly concerned that these school choice measures are either taking funding away from public education and therefore depleting their already strained resources or that the alternative forms of education lack sufficient regulation and oversight.
Split into simpler sentences: Public school entities are chiefly concerned that these school choice measures are either taking funding away from public education and therefore depleting their already strained resources. Alternatively, public school entities may argue that non-traditional forms of education lack sufficient regulation and oversight.