WASHINGTON — Slow, grinding negotiations on a huge COVID-19 relief bill are set to resume Monday afternoon, but the path forward promises to be challenging and time is already growing short. Republicans are griping that House Speaker Nancy Pelosi won’t drop her expansive wish list even as concerns are mounting that the White House needs to be more sure-footed in the negotiations. Both the Trump administration negotiating team and top Capitol Hill Democrats remain far apart, and talks since Saturday — when the combatants announced modest progress — have yet to lend momentum.