When President Obama delivers his speech Wednesday on how he plans to have the U.S. combat the Islamic State, he may have to explain whether he plans to ask Congress for authorization to widen military strikes against the group.

"I'm confident that I have the authorization that I need to protect the American people," Obama told NBC's Chuck Todd in an interview that aired on Sunday. "And I'm always going to do what's necessary to protect the American people. But I do think it's important for Congress to understand what the plan is, to have buy-in, to debate it."

On Tuesday, Obama is expected to meet with U.S. Senate Majority Leader Harry Reid, D-Nev.; Senate Minority Leader Mitch McConnell, R-Ky.; Speaker of the House Rep. John Boehner, R-Ohio; and House Minority Leader Rep. Nancy Pelosi, D-Calif.

Since Aug. 8, the U.S. has launched more than 140 airstrikes in Iraq to protect the lives of American personnel in Baghdad and Irbil and to stop Islamic State fighters from killing members of the minority Yazidi sect. The War Powers Resolution, also known as the War Powers Act, requires the president to end any military action within 60 to 90 days of commencement if it has not been authorized by Congress, but that is not a hard deadline.

"No president has ever recognized the constitutionality of the War Powers Act," said Mieke Eoyang, director of the national security program at Third Way, a centrist think tank.

Congress passed the War Powers Resolution in 1973 over President Nixon's veto. It lays out the procedures that the president and Congress must follow when U.S. troops are introduced into an armed conflict.

The timeline established by the War Powers Resolution gives Congress until Nov. 8 to approve operations against the Islamic State. After that, "you get into a little bit tricky legal territory," Eoyang told Military Times on Monday. Still, she does not think Congress plans to end funding for military operations against Iraq to make a point about enforcing the War Powers Resolution.

"I don't think that's politically where Congress is," she said. "I think a lot of people recognize the threat of ISIS [the Islamic State of Iraq and al-Sham]. It's not a question of whether to act but when and how."

The previous two authorizations for use of military force passed by Congress do not squarely apply to the Islamic State, Eoyang said. Congress' approval for military force in Iraq prior to the March 2003 invasion was directed toward Saddam Hussein's regime. And Congress has given the president the power to combat the groups behind the Sept. 11, 2001 attacks, but al-Qaida has expelled the Islamic State from its franchise.

"I think it is in the best interests of the nation that Congress pass some kind of authorization to demonstrate the American people's support for dealing with ISIS," Eoyang said.