Call it a sad sign of party unity: Not a single Democrat voted Tuesday to advance Rep. Alexandria Ocasio-Cortez’s Green New Deal resolution in the Senate.

Senate Majority Leader Mitch McConnell put the measure up for a vote to force Democrats to make a public stand on it — and they punted. Original co-sponsor Sen. Ed Markey (D-Mass.) joined 42 other Dems, including all six of the Senate’s 2020 contenders, in voting “present.” Six Democrats and all Republicans voted “nay.”

Supposed supporters of the Green New Deal complained that having a vote on the bill was a “stunt” — but then what’s the point of writing it in the first place?

The real problem is that the GND’s “ideals” are actually disasters. Set aside all the blather about creating new jobs and vastly boosting social justice: At its core is the drive to end all US greenhouse-gas emissions by 2030 — which means shutting down much of the economy.

Stop all burning of coal, oil and natural gas? Renewable energy (even if you include nuclear power) simply can’t scale up in time — and would cost far more.

In short, a bill encapsulating the dreams the Democratic base — at least the urban Democratic Socialists of the AOC wing — is so toxic that no senator dares vote for it.

Sen. Chuck Schumer (D-NY) insisted that the maneuver shows that Republicans have no plan “to deal with the threat of climate change.” But if the Green new Deal isn’t worth voting on, neither do the Democrats.