What to Expect From Obama's Big Speech on the Islamic State Tonight

President Obama is set to deliver a speech Wednesday evening outlining his long-term strategy for dealing with the Islamic State.

The New York Times reports that Obama is prepared to authorize airstrikes in Syria two weeks after announcing manned and unmanned surveillance flights over the country. That will likely come paired with more support for anti-IS fighters in Iraq and, potentially, Syria.

Obama has spent the past few days lobbying other leaders on the plan, from fellow NATO members in Wales to foreign-policy bigwigs on Monday and congressional leaders on Tuesday. There are still a few major questions that the president will have to address in Wednesday evening's speech or in the coming days as the policy takes shape.

The biggest challenge is how to weaken IS in Syria without helping its enemy, Syrian President Bashar Assad. Obama has called for Assad to step down for years, and his regime's likely atrocities committed in the country's civil war mean the U.S. isn't going be friendly just because both countries share a common enemy. Coincidentally, Wednesday's address falls one year to the day after Obama's last prime-time speech on Sept. 10, 2013, in which he updated the nation on potentially striking chemical weapons sites in Syria.

One possible solution that's being discussed in Congress is funding a more moderate group of rebels to fight IS, as noted by the Times. Enabling a moderate group to defeat IS, this thinking goes, would create a counterweight to Assad's regime in the aftermath. But there's no clear third party, just multiple factions, and identifying and funding rebel groups is a tricky proposition.

Another issue is how much international cooperation the U.S. can muster. While the new Iraqi government has a clear incentive to take on IS, a country like Turkey can be harder to persuade. IS is currently holding 49 Turkish diplomats hostage, leading the country's government to tread lightly to avoid executions. Another potentially valuable ally, Saudi Arabia, is threatened by IS but has not yet worked closely with the U.S. to address its spread elsewhere.

Obama nipped one potential challenge in the bud by steadfastly declaring his authority to conduct military strikes inside Syria without congressional approval.

"The President told the Leaders that he has the authority he needs to take action against ISIL in accordance with the mission he will lay out in his address tomorrow night," the White House said in a statement following Obama's meeting with congressional leaders on Tuesday. "The President told the Leaders that he would welcome action by the Congress that would aid the overall effort and demonstrate to the world that the United States is united in defeating the threat from ISIL."

Public opinion is on the president's side. Following the shocking beheading videos of American journalists James Foley and Steven Sotloff, a majority of Americans are in favor of airstrikes against the group — 71% support strikes in Iraq, and 65% support them in Syria, according to a new Washington Post/ABC News poll.

Obama may be addressing the American people Wednesday night, but if he was able to secure the support of world and congressional leaders he's already met with, he may not need to convince anyone else.