On Wednesday OPEC will try to nail down the particulars of a September deal to reduce the global oversupply of oil, but Iran, Iraq and Russia are presenting some serious roadblocks.

Saudi Arabia is pushing for an output cut totaling more than 1% of the global oil supply from OPEC members, while also calling for substantial cuts from producers outside the cartel, most importantly Russia, the Wall Street Journal reports. But Russia relies on oil and gas for nearly half its revenue, and due to Western sanctions the country has little room to make cuts.

Iran and Iraq aren’t eager to jump on board. Iran is looking to regain market share by building relationships with European refineries and Asian buyers while Iraq is pumping every barrel it can to fund its war against the Islamic State, making both countries unlikely to agree to substantial cuts. [WSJ]