The interesting thing is how the reaction of the left has changed little in a quarter of a century...
That's because the motivating principle- hatred of America and contempt for the majority of its citizens- hasn't changed at all.
Yes, he wants "greater effort" to bring allies into the effort, which effort? THE EFFORT TO MAKE A DECLARATION ABOUT WHAT ARE AMERICAN INTERESTS!
That in itself does not even make sense. A declaration even has to refrain from unilateralism. This is not a practical concern [that is, it has nothing to do with the needs or risks in a specific situation], it occurs at the philosophical level. America must not speak in its own voice. Its voice [and action] must be muffled through the consensus of others' interests and voices.
[This also relates to the premise of his diplomat father who wrote a book advancing this premise of non-unilateral speech and action]
This reflex in Kerry must not be simply ambivalence or fip-flopping or indecision, I think it is an inveterate tactic in how he seeks to get in the way of American purpose, to deflect it, to distract it, to delay it, to weaken it, ultimately, to defeat it.
The same thing that both he and the French were about in the pre-Iraq war period, are this tactic.
This is essentially a belief of utter opposition to the premise of American exceptionalism. This is how he is one with the French. It is why he does not ever want us to act by ourselves. He won't say that this is the reason [he has to hide this fact at all costs, because it is political suicide], which is really to say that he does not want American interests to prevail.