It may have appeared an extraordinary blue wave as Democrats won a clean sweep of the major offices up for grabs on Tuesday night - two state governorships and the jewel in the crown, the mayoralty of New York City.

Jubilant left-wingers declared their party is now over the catastrophe of 2024 when they were trounced by Donald Trump and lost both chambers of Congress.

They claimed the results would be a launchpad for surging to victory in the midterm elections next year, and that they represented a damning referendum on the first 10 months of President Trump's administration. The Democrats are back and firing on all cylinders, it seemed.

However, the night also lit the fuse on a potentially devastating civil war for the heart of the Democratic Party that may well come to overshadow the gains it made this week.

Both a radical far-left candidate, Zohran Mamdani in New York, and a pragmatic centrist, Abigail Spanberger in Virginia, stormed to victory, setting up two very different visions for the future.

That threatens to tear the party asunder as other candidates decide which path to follow - the intransigent, Trump-baiting democratic socialism of Mamdani, or the hardheaded realism and appeal to independents represented by Spanberger.

The two candidates were so far apart that they cannot both be the way forward for Democrats.

Now, the internecine struggle between Mamdani's emboldened leftists and the centrists threatens to be messy, bitter and self-destructive. 

Meanwhile, on the Republican side, there was also a stark lesson learned. The party's candidates found that simply aligning themselves with Trump failed to get voters to the polls in large numbers when the president himself is not on the ballot.

Trump did not campaign in New York, Virginia or New Jersey and the impact of his absence was clear, with a lack of enthusiasm pervading Republican campaigns.

It was an ominous warning for Republicans that Trumpism without Trump may not be enough to win next time.