Modify the paragraph with different wording.
The reluctance of developing countries to commit themselves to more demanding policies before they see clear leadership from industrialised countries, combined with the lack of such action from important industrialised partners who are not Parties to the Kyoto Protocol, is likely to prevent this from happening.
This is even less likely that developing countries are hesitant to commit in a more demanding way when they don't see a clear lead role for industrialized countries or any similar measure for the relevant industrial partners not party under the Kyoto Protocol.