The New York Times and the Washington Post said Obama is willing to expand to Syria the campaign of airstrikes that the United States has so far limited to IS targets in Iraq over the past month.
The Islamic militant group has captured vast expanses of territory in both countries.
The Times quoted a senior administration official and the Post cited foreign policy experts who met with the president this week.
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Obama is to lay out his strategy for fighting IS in a prime-time speech to the nation Wednesday evening.
Michele Flournoy, a former undersecretary of defense for policy under Obama who was among those who attended a dinner with him Monday, said the president is determined to fight the Islamic State "wherever their strategic targets are", according to the Post.
"This is not an organization that respects international boundaries," said Flournoy, who left the administration in 2012. "You cannot leave them with a safe haven.. . . I expect him to be very candid."
The Times said that people briefed on the president's plans described "a long-term campaign far more complex than the targeted strikes the United States has used against Al-Qaeda in Yemen, Pakistan and elsewhere."