WASHINGTON — Bernie Sanders’ revolution was on the ropes Wednesday as the self-described socialist now must combat unfriendly turf as he seeks to reverse a string of shocking primary losses.

The 78-year-old elected to remain in the race Wednesday despite now standing a distant second to former vice president Joe Biden, who again this week swept key contests in the south and won the Midwest.

The road ahead doesn’t look any smoother for Sanders.

His 2016 rival, former Secretary of State Hillary Clinton, scored large wins in major states that have yet to vote in the Democratic primary fight, like Florida, Georgia, Pennsylvania and New York.

In delegate-rich Florida, Biden is polling ahead of Sanders and has snatched the support of Latino voters who were aggrieved by Sanders’ words of praise for Cuban Communist dictator Fidel Castro.

“I don’t see that territory being particularly friendly to him,” said University of Buffalo associate professor of political science Jacob Neiheisel. “I think he was pinning his hopes on places he won last time and that really didn’t seem to pan out.”

Even if he were able to score wins, the Democratic Party awards delegates proportionally, making it more difficult to overcome a deficit late in the contest.

Biden currently has 857 delegates, compared to Sanders’ 709, according to a tally kept by the Associated Press. A candidate needs 1,991 delegates to become the Democratic nominee.

“I think he stays in after the debates hoping for some kind of game change but that would be unusual,” said Neiheisel, who speculated that Sanders could be out as soon as April.

Addressing the media on Wednesday after Biden’s string of victories on Tuesday evening, Sanders acknowledged his long odds but vowed to stay in the race to keep pushing his progressive agenda.

Veteran strategist Bob Shrum, who ran John Kerry and Al Gore’s White House bids, also didn’t see any big victories in Sanders’ future.

“Bernie will romp in Florida. He could win by 50 percent as he did in Mississippi. He will win Ohio,” Shrum told The Post.

The Vermont senator failed to garner the support of the Democratic Party’s large base of black voters on Super Tuesday and was this week shunned by voters in the rural Midwestern states of Missouri and Michigan.

“The landscape is now not favorable at all to Sanders because you do those two states and then Georgia and then Pennsylvania. These are all states that are good for Biden,” Shrum added.

The Democratic establishment and Democrat voters have coalesced around Biden in the past week and the 77-year-old is riding high after a string of coveted endorsements and big wins in recent primary races.

Both Neiheisel and Shrum predicted Biden would win the delegates needed to become the nominee.

“I don’t think he has a whole of a shot absent of a game change,” Neiheisel said of Sanders’ White House dreams.