Global security is a pretty good reason not to let him go it alone…..
Check it out:

Sen. Lindsey Graham (R-S.C.) attempted Thursday to force a vote on legislation that would give Congress a vote on any nuclear deal negotiated with Iran, warning of the dangers of a nuclear-armed Iran and saying that “this is not the time to let President Obama go it alone.”

Graham said on the Senate floor that, in his view, Obama “wants a deal too badly.”