Jack Goldsmith analyzes the Senate’s draft Authorization for Use of Military Force (AUMF), which is narrower than the administration’s AUMF. The Senate’s language on ground troops:

Ground Troops “Limitation.”  Section 3 of the draft provides: “The authority granted in section 2 does not authorize the use of the United States Armed Forces on the ground in Syria for the purpose of combat operations.”

This is a limit on the authority conferred by Congress in Section 2, and not a limit on the President’s independent constitutional power to send ground troops into Syria, even for combat purposes.  Section 3 merely says that the congressional approval of the use of presidential force in Syria does not entail approval for the use of ground troops in Syria.  But it does not speak to, much less prevent, the President from using ground troops on his own authority.

Moreover, even the ground troop limitation on Congress’s authorization contains an exception for ground troops introduced into Syria for a purpose other than “combat operations.”  In other words, Sections 2 and 3 in combination affirmatively authorize the President to introduce U.S. ground troops in Syria for non-combat purposes if he thinks they are necessary and appropriate to achieve the purposes of the authorization. Section 3 is probably written this way to capture the fact DOD Special Operations Forces are being used in Syria, or will be used there, for intelligence-related and other “preparation of the battlefield” tasks.  (I imagine, but of course do not know, that this is a nod to operational reality, since DOD has probably already sent Special Operations Forces into Syria, under the President’s Article II power, to prepare the battlefield.) It is also probably meant as a carve out for search-and-rescue missions, and the like, if necessary.

Andrew Rudalevige also parses the document. On the time limitations:

[T]he resolution says in one of its “whereas” clauses that “the President has authority under the Constitution to use force in order to defend the national security interests of the United States.”  If not quite as broad as the parallel clause in the September 2001 AUMF (“the President has authority under the Constitution to take action to deter and prevent acts of international terrorism against the United States”) it nonetheless seems out of place in a series of “whereases” justifying the resolution in the first place.

If the president does have such authority under the Constitution, unfettered by others’ judgment about what the national security interests of the United States might entail, putting it in statutory language has no effect. If he does not, the clause does not make it so—but it does provide another useful piece of ‘legislative intent’ presidents can point to in future iterations of this interaction. Since in the resolution at present what expires after 60 (or 90) days is the congressional authorization for the operation, not the operation itself, there seems to be a backdoor permission here to continue the latter even after that time, under ongoing claims to “national security interests.”