An interesting development over the last few games for the surging Rangers:

And that is, as the March 2 trade deadline approaches, the Blueshirts’ primary need is for a reliable left defenseman to partner on the third pair with Dan Boyle rather than a bottom-six forward to bolster the team’s depth up front.

Getting both would, of course, be optimal, but general manager Glen Sather may not have the cap space or the expendable assets with which to pull off the double. And if the Blueshirts — who moved into second in the East and fifth overall in points per game following Monday’s thrilling 6-5 victory at the Coliseum, trailing only acknowledged Cup front-runners Nashville, St. Louis, Montreal and Anaheim — can fill only one hole, then it has to be on the blue line, where the John Moore-Matt Hunwick rotation has grown increasingly deficient under pressure.

To that end, sources have told The Post the Blueshirts have joined a crowded field dreaming of acquiring Carolina’s Andrej Sekera as a rental property. The price at this point, sources said, is a first-rounder plus a prospect, which is too rich for just about any suitor’s blood, and certainly Sather’s.

But chances are that the price will drop, and if it does, there is no reason the Rangers shouldn’t be willing to offer one of their two second-rounders (their own or Tampa Bay’s) and a prospect not named Anthony Duclair, Pavel Buchnevich or Brady Skjei.

If the Hurricanes like Moore, who still has fair upside despite this downer of a season, then by all means, there would be no reason not to include the 24-year-old in the package if it would seal the deal for Sekera, who has played the last two seasons paired with Justin Faulk on Carolina’s first pair.

Sekera, though, is the prime left defenseman on the rental market, so the Candy Canes — who scouted the Rangers in Arizona on Saturday just as the Blueshirts scouted Carolina in Ottawa on Monday — hold the cards and can be expected to be patient.

Rental prices are high, even in what might be considered a buyers’ market given the large number of sellers approaching the deadline. The Post has been told by several individuals the Maple Leafs last week asked the Rangers for a second-rounder plus a prospect for Mike Santorelli before Toronto included the forward in the package with Cody Franson that went to Nashville for a first-rounder, a prospect and Olli Jokinen.

Just as the Blueshirts have been scouring the league for bottom-six help, lo and behold, Tanner Glass played two of his most effective games of the season against the Coyotes and the Islanders. Maybe these two games signify the start of something better ahead for the fan base’s whipping boy. Maybe it is not so far-fetched Glass could fill a postseason role.

Regardless, the Rangers would still need depth — two injuries up front in the playoffs and who would step in? Chris Mueller? Chris Bourque? — but it is more critical that they address their third-pair issues.

Over the last 31 games, Hunwick and Moore have each been in the lineup 16 times, including Saturday’s match in Arizona for which both dressed when Boyle was ill. Contrary to coach Alain Vigneault’s public pronouncements, neither is playing well in this rotation.

When a team rotates its sixth and seventh defensemen, it has two seventh defensemen. The Rangers need better than that in order to get through three playoff rounds and advance to the fourth.

As the deadline approaches, as the season moves toward the quarter pole, it is time for Vigneault to go with Moore on a daily basis and see if he can be rehabilitated toward the end of a season that never got back on track following his early November suspension for a shot to the head of Erik Haula.

Hunwick is a journeyman who has done his best filling in. But he is small and not quick enough in his decision-making under pressure that increases by the week as the season heads to the stretch. Moore, on the other hand, did play a regular role last year for the team that went to the final. There is more there than Moore has shown this year.

The Blueshirts have as good a shot as anybody in the East to compete for the Stanley Cup, where there are no 2000 Devils, 1982 Islanders or 1977 Canadiens in the way of the defending conference champions.

When play began Tuesday, the Rangers were not only second in the East and fifth in the NHL in points per game, they were second in goals per game, fourth in goals-against, and first in goal-differential (subtracting shootouts from the equation).

Which is to say there is no reason, within reason, for Sather not to be all in at the deadline. This team is legit.

There is no reason for the Rangers not to be competitive in an attempt to get Sekera, a player whose acquisition — still probably a long shot given the number of young players, including J.T. Miller and Jesper Fast, the GM would quarantine — would fill the team’s most glaring need.