Kamala Harris gives a star performance during the Democratic presidential debate and proves she can take on Trump

We are six months away from the first votes being cast by Democrats for their presidential nominee.

And not until the summer of 2020 will the battle-hardened candidate be crowned and ready to face Donald Trump.

So this is a marathon and not a sprint. But Thursday’s night Democratic presidential debate was an eye opener and sets up a tantalising possibility.

Joe Biden looked old and out of touch.

He has a long political and legislative record to defend and did it poorly on stage.

He is already accused of having been too close and friendly with segregationists, and of being too tactile with women for the #MeToo era.

But that in a way was not the story of the fiery Thursday night debate.

The real revelation (though some who know her best say it should not have come as a surprise) was Senator Kamala Harris.

She was on fire, delivering some well-timed lines and launching a forensic attack on Joe Biden’s civil rights record.

Already there is a buzz that she could win the party’s nomination and be an excellent match-up against Trump in the 2020 presidential race.

Pete Buttigieg, mayor of South Bend, Indiana. Credit: AP

There is another game being played in Democratic and media circles (a game because it’s clearly - even absurdly - premature): Who would Harris choose as her vice presidential pick?

Some insiders are speculating it could be Pete Buttigieg, the 37-year old mayor of South Bend, Indiana, who is impressing everyone who encounters him.

Just for a moment imagine that presidential ticket.

A half-Jamaican, half-Indian female prosecutor from California, married to a Jew, running on a ticket with a military veteran, millennial, gay, Episcopalian city mayor from the Midwest.

Now picture that combination ranged against Trump and Pence. You can see why American progressives are intrigued (and, yes, journalists too).

Harris and Buttigieg against Trump and Pence.

That would be a political, generational, and ideological clash for the ages.

Race, gender, identity politics, and the future of America would all be on the ballot.