Donald Trump’s recent rhetorical fumble in which he confused Nikki Haley and Nancy Pelosi has begun raising concerns about media coverage of the leading Republican presidential candidate’s mental state. New Republic editor Michael Tomasky, in a five-alarm missive condemning the coverage of Trump’s startling weekend statement, asked readers to imagine what would have happened if President Joe Biden publicly confused a campaign opponent with a past speaker of the House. “Things might well cascade to the point that Biden would have to stand down,” Tomasky writes. “But when Trump says it — it’s no…