Turkey's prime minister says "more active steps" to end Syria's civil war will be a key topic when he meets with President Obama at the White House Thursday. "The Syrian issue will of course be the first topic on the agenda," Recep Tayyip Erdogan told reporters before leaving Ankara. "We will discuss what we can do for the future and what more active steps we can take," he said, adding he expected he and Obama would "draw a road map" during their 9:50 a.m. EDT meeting in the White House Cabinet Room. Erdogan said he planned to present evidence at the meeting, which Vice President Joe Biden also is to attend, of Syrian chemical weapons use to strengthen his case. Obama has said proof of chemical weapons use by Syrian President Bashar Assad's forces would be a "red line" and a "game-changer," but has so far said the evidence of such use was insufficient to prompt U.S. action or enable him to unite U.S. allies behind such a response. Turkey has NATO's second-largest army. Obama and Erdogan agree on broad goals in Syria, with both saying Assad must go, as more than two years of violence has left more than 70,000 people dead. But they disagree on their approaches to Syria, with Obama resisting Erdogan's pushes to provide military assistance to rebels trying to oust Assad. Erdogan told NBC News a week ago he wanted Washington "to take more responsibility, further steps inside, in Syria, to end the fighting." One way would be for the creation of a U.S.-enforced, no-fly zone in Syria, Erdogan told the network, which would prohibit Syrian military aircraft from hitting rebel targets. But setting up a no-fly zone would at minimum require U.S. air strikes, which the Obama administration does not want to do, U.S. officials say. "It is our position, as of now, that our assistance to the Syrian opposition is non-lethal in nature, although it has changed in kind within the rubric of nonlethal," White House spokesman Jay Carney said Wednesday, adding the administration was "constantly evaluating what our options are." "You heard the president talk about this and the need to make sure that the actions we take help bring about the goal that we seek, which is a Syria that is rid of Bashar Assad; a Syria that has the opportunity to flourish, to be more democratic and more prosperous; to have a government that reflects the will of the people and respects the rights of all the Syrian people," Carney said. "Those are substantial goals and we need to make sure that the actions we take contribute to the achievement of those goals on behalf of U.S. national interests, as well as, importantly, the Syrian people." The two leaders are also expected to talk about overall Middle East stability, including in Iraq and Iran, both of which border Turkey, and Turkey's emerging reconciliation with Israel. They are additionally expected to discuss U.S.-Turkish economic cooperation and countering global terrorism overall, the White House said. Obama and Erdogan scheduled a noon news conference at the White House Rose Garden, the White House said. They plan a working dinner at 6:30 p.m.