DES MOINES, IOWA — The results from the Iowa caucus are still shrouded in mystery, but one thing is becoming clear: It was not Joe Biden’s night.

Entrance polls had the former vice president hovering around 15 percent across the state, while Biden would have been immediately ruled nonviable at a downtown Des Moines precinct if he didn’t get help from an unlikely source: Cory Booker.

Biden’s turnout was so bad at the Des Moines 65 caucus site that a cunning Elizabeth Warren precinct captain had to do some frantic last-minute horse-trading to keep him in the race and stop Biden’s supporters from joining Pete Buttigieg’s huge camp, the Warren staffer told The Post on Monday night.

Seven Booker caucus-goers showed up symbolically at the Lincoln High School cafeteria knowing their votes wouldn’t count after their candidate dropped out last month.

Before the first count, Warren staffer Jamie Yowler, 30, realized Biden was nonviable and was concerned that the 55 Biden devotees gathered would walk over to Buttigieg’s 88 supporters — the largest group in the room.

“Buttigieg would have picked up four delegates, only leaving one for the rest of us,” Yowler told The Post, explaining how he convinced some Booker supporters to cast a pity vote for Biden for the sake of Bernie Sanders and Warren.

Candidates are competing for delegates who will determine the fate of the primary at the Democratic National Convention in June.

Amy Klobuchar was also immediately ruled nonviable in Des Moines 65 and Yowler feared the only place left for moderate Biden supporters to go was with Buttigieg, another moderate Democrat, he said.

The unscientific horse-trading gives an insight into how the rest of the race might have played out across Iowa on Monday night and how the Democratic primary will shape up.

Buttigieg was quick to declare victory Monday despite the caucus chaos, and on Tuesday morning claimed his data showed he had won precincts that went to President Trump in 2016.

Des Moines 65 — while just one of 1,681 precincts — shows that Buttigieg could be a real problem for Warren with Biden and Klobuchar out of the race.

The former mayor of South Bend, Indiana, seems poised to pick up their supporters, setting up a potential two-way race between him and Sanders.

Interestingly, Sanders carried Des Moines 65 in 2016, with locals telling The Post the district was relatively progressive.

Buttigieg won it this year with 109 voters, compared to Sanders’ 89.

The results from the caucus are expected to be released Tuesday after a systemic meltdown that forced candidates to leave for New Hampshire without Iowa results for the first time in history.

The Klobuchar, Sanders and Buttigieg campaigns have all released figures claiming they performed better than expected.

However, entrance polling showed a poor turnout for Biden, who was barely viable across the state with just 15 percent of the vote, Politico reported Monday night.