Rangers GM Glen Sather has indicated how important it is for the team to lock up Girardi and Callahan to new deals, as both players can become unrestricted free agents this summer.
"I think I've said this before: We want to re-sign all of these players, and we'd like to get it done before the season is finished if we can," Sather said on a conference call, as quoted by the New York Post. "We've had discussions with their agents and hopefully we will get it done. But this (trade for Klein) does give us a little more insurance on that side, so you have to look to the future as well when you do make these deals."
Girardi, 29, is expecting a significant raise from the $3.325 million annual salary cap hit he's earning now.
If he hits the open market in July, Girardi should clear at least $5 million per season.
Sather must decide whether or not to trade him, if the two sides cannot come to terms on a new contract by the March 5 trade deadline.
The Rangers have already had trade discussions with the Anaheim Ducks about Girardi, while several other teams have inquired about his services.
Callahan, 28, is making $4.825 million this season, though his cap hit is $4.275 million, and will see his salary climb, as well.
Sather also has a decision to make on his captain, but with the team in the thick of things in the standings and battling for home ice advantage in the playoffs, it's unclear if the Rangers are willing to move two key assets without replacing them.