Desperation propelled the Rangers to a furious, final 20 minutes last night at the Garden. Now the same sense of urgency following a fourth straight defeat must propel the Blueshirts to a consistent 60 minutes a night of similar effort in order to prevent the season from slipping away.

“I don’t see why we can’t play 60 minutes of desperate hockey,” Ryan Callahan, who was immense in every conceivable aspect of last night’s 4-3 defeat to the Jets, told The Post after his team’s slide reached 0-3-1. “We’ve played that way and won that way before, so obviously it can be done.”

Rick Nash might be able to return to the lineup as soon as tomorrow night after missing the last four games (believed concussion-like symptoms) when the Lightning come to the Garden. Michael Del Zotto, who missed his second straight with a lower body issue, could conceivably return then as well, and tomorrow would probably be optimistic for Ryan McDonagh (believed concussion-like symptoms).

A nearly full squad could turn the Blueshirts’ pitcher to half-full from the half-empty 8-8-2 start — well, more stops than starts so far — that includes a 1-3-2 slide over the last half-dozen matches.

Last night’s third period, in which the Blueshirts played with fortitude and a sense of purpose in dominating Winnipeg only to be undone in large measure by a shockingly soft fourth goal allowed by Henrik Lundqvist, could provide a platform for this team that is seeking equilibrium.

“I think that a desperate third period like we played helps us to develop the belief we need in ourselves,” said Marian Gaborik, who has scored only one goal in the last eight games. “We have to take the good out of this and not get down.”