Multiple outlets reported last week that the Rangers have granted other teams permission to speak with Callahan's agent, who recently received a five-year, $30 million offer for his client, pitched by the Rangers.
Callahan is believed to be asking for a seven-year contract worth in between $6.5 million and $7 million, per season.
Callahan's agent Steve Bartlett told ESPNNewYork.com on Monday morning that "I'm going to circle back with the Rangers this week."
According to TSN Hockey Insider Darren Dreger, the St. Louis Blues are among the teams interested in Callahan, and would like to package right wing Chris Stewart, as part of a deal, for him.
In 39 games with the Rangers so far this season, Callahan has collected nine goals and 12 assists for 21 points.