The 38-year-old reliever, who was squeezed from the Opening Day roster by Blaine Boyer, has been told his situation will be reevaluated within two weeks.
"I've come this far, two more weeks won't kill me," said Isringhausen, who last pitched in the major leagues in 2009.
The Mets have told Isringhausen they will release him from his minor league contract if another team wants him before extended spring training concludes. But the Mets also have right of first refusal, meaning they could block Isringhausen from joining an NL East rival such as the Phillies, who could seek bullpen help with closer Brad Lidge expected to miss 3-6 weeks.
Isringhausen, who posted a 1.13 ERA in eight spring training appearances, said he wasn't upset with the Mets' decision to leave him off the Opening Day roster.
Johan Santana said it will be "tough" remaining behind at the Mets minor league complex this spring, but he fully expects to return and help the team in 2011. The lefty is continuing his rehab from shoulder surgery, but is not close to throwing from a mound. The Mets are hoping he can return by late June.
"I'm very pleased with how I feel," Santana said. "It feels like everything is getting looser, looser and looser as I throw -- and better."
In other news, Nick Evans cleared waivers and was out-righted to Triple-A Buffalo. Luis Hernandez also cleared waivers and must decide if he will accept an assignment to Buffalo. General manager Sandy Alderson said he expects Hernandez to accept.