Donald Trump is sweeping all before him in the race for the Republican presidential nomination, but the primary votes have unveiled some worrying obstacles in his path to a second term in the White House.

Despite having a virtual lock on the nomination ahead of this week's 15-state "Super Tuesday" voting bonanza, the 77-year-old has been hemorrhaging moderate Republicans, who have signaled they'd prefer someone else — anyone else — in the Oval Office.

His double-digit victories over Nikki Haley in the early voting states have also obscured flashing red lights over his standing with the independents he'll need to prevail against President Joe Biden in November.