After a delay game that looked like it would never end, former Vice President Joe Biden is expected to officially launch his 2020 presidential run Thursday with an online video.

That brings the number of Democratic can­didates to at least 20, and means all the real contenders are now off and running.

Yes, there may be one or two more hats ready to be tossed into the ring — but no one who needs be taken very seriously.

In making his third try for the presidency, Biden immediately moves to the head of the pack, alongside his fellow septuagenarian, Sen. Bernie Sanders.

Question is, which Joe Biden is running?

Biden has spent nearly half a century in Washington, with a lengthy and often commendable record as a standard Democratic liberal — though decidedly more moderate than the current crop of contenders.

Yet he’s spent the past two years running away from much of that record and apologizing for past positions, like his support for the Iraq war and 1990s anti-crime legislation, as well as actions like his handling of Anita Hill’s testimony against Clarence Thomas.

Having served two terms as Barack Obama’s vice president, he’d love to offer himself as, in effect, Obama’s third term.

But that means standing up to the angry lefties who now dominate the Democratic base and no longer hold the nation’s first African-American president in much esteem.

With most of the pack running left, Biden’s strongest argument to Democrats is that he’s their best hope of beating President Trump — but he weakens that case, and loses working-class appeal, every time he makes another concession to the loons.

As soon as Biden decides, the Democratic race is set.