By David Morgan and Makini Brice WASHINGTON (Reuters) -Republicans in the U.S. House of Representatives struggled with a second day of division on Wednesday as a stubborn band of holdouts refused to back Kevin McCarthy’s bid to lead the chamber, defying former President Donald Trump’s call for unity. Despite Trump’s appeal, McCarthy fell short in a fourth vote for House speaker and was on track to lose a fifth vote as well, as roughly 20 Republicans on the party’s right flank refused to back a candidate they saw as ideologically unreliable. McCarthy, a congressman from California who has serve…