Just three days before the US House of Representatives chooses its next speaker, Republican Mike Johnson is in an increasingly nerve-racking fight to keep his gavel amid mutterings of rebellion on his right flank. President-elect Donald Trump endorsed Johnson on Monday but even that may not be enough for the 52-year-old Louisiana conservative to win over the lower chamber of Congress, where the razor-thin Republican majority can afford almost no dissent. A chaotic 2023-24 session was marked by...