It depends what you call cooperate ?
If Jack is asking for the moon, it's hard to see how you can cooperate if this is what your asking.
When he says cooperate, I believe he's talking about Layton having one goal or one plan, Harper having his own goal & plan, and both of them negotiating & cooperating with one another to reach a compromise.
...... instead of the old routine of Harper saying he'll work with the other parties, when in reality he shoves his plans down everybody else's throat and tells them to accept it as it is, or I'll screw you over somehow.
That's not cooperation.... that's thuggery.