WASHINGTON (AP) -- As a U.S. senator running to become president in 2007, Barack Obama sponsored a resolution to prohibit President George W. Bush's administration from taking military action against Iran unless it was explicitly authorized by Congress.
His idea did not become law.
In the past five weeks, U.S. fighter jets and unmanned drones armed with missiles have, under Obama's presidential orders, conducted more than 150 airstrikes against the Islamic State group in Iraq, even as the White House has yet to formally ask Congress for authorization to expand the air campaign.
In an address to the nation Wednesday, Obama said he had authorized U.S. airstrikes inside Syria for the first time, along with expanded strikes in Iraq, as part of "a steady, relentless effort" to root out Islamic State extremists. He did not say how long he expected the fighting to last.
The White House says Bush-era congressional authorizations for the war on al-Qaida and the Iraq invasion give Obama the authority to expand the fighting in Syria and Iraq without new approval by Congress under the 1973 War Powers Act.
That law serves as a constitutional check on the president's power to declare war without congressional consent. It requires presidents to notify Congress within 48 hours of military action and limits the use of military forces to no more than 60 days unless Congress authorizes force or declares war.
Critics say the administration's tightly crafted legal strategy has short-circuited the congressional oversight that Obama once championed.
White House spokesman Josh Earnest on Thursday cited the 2001 military authorization Congress gave Bush to attack any countries, groups or people who planned, authorized, committed or aided the Sept. 11, 2001, terrorist attacks.
Earnest says Obama believes the authorization "continues to apply to this terrorist organization that is operating in Iraq and Syria."
The Islamic State group, which was founded in 2004, has not been linked to the 9/11 attacks, although its founders later pledged allegiance to Osama bin Laden. In February, al-Qaida declared that the Islamic State group was no longer formally part of its terror organization.
And in recent weeks, senior U.S. officials, including Homeland Security Secretary Jeh Johnson and Matthew Olsen, head of the National Counterterrorism Center, have drawn significant distinctions between al-Qaida and the Islamic State group.
Earnest said Thursday that Obama welcomes support from Congress but said it wasn't necessary.
"The president has the authority, the statutory authority that he needs," Earnest said.
"I actually think the 2001 AUMF argument is pretty tortured," said Representative Jim Himes, a Democrat from Connecticut who serves on the House Intelligence Committee. "They are essentially saying that ISIL is associated with al-Qaida, and that's not obvious."
Himes supports a new congressional vote, as does another Democrat on the Intelligence Committee, Representative Adam Schiff of California.
The White House also finds authorization under the 2002 resolution that approved the invasion of Iraq to identify and destroy weapons of mass destruction. That resolution also cited the threat from al-Qaida, which Congress said then was operating inside Iraq. But the U.S. later concluded there were no ties between al-Qaida and Iraqi President Saddam Hussein or his government. In addition, the group formally known as al-Qaida in Iraq -- which later evolved into the Islamic State group -- didn't form until 2004, after the U.S.-led invasion.
Obama uses both authorizations as authority to act even though he publicly sought their repeal last year.
Obama himself said Wednesday that he wants congressional backing, not for U.S. airstrikes but for the buildup of American advisers and equipment to aid Syrian opposition forces. House Republicans spurned a vote on that request earlier this week. The White House acknowledged that it could not overtly train Syrian rebels without Congress approving the cost of about $500 million.
"Committing American lives to war is such a serious question it should not be left to one person to decide, even if it's the president," said former Illinois Representative Paul Findley, 92, who helped write the War Powers Act.
Since U.S. military advisers went into Iraq in June, the administration has maneuvered repeatedly to avoid coming into conflict with the War Powers law. Seven times, before each 60-day limit on using military forces has expired, Obama has sent new notification letters to Congress restarting the clock and providing new extensions without invoking congressional approval.
Associated Press writer Ken Dilanian contributed to this report.
2001 AUMF: http://tinyurl.com/8kzyw2k
2002 Iraq joint resolution: http://tinyurl.com/3hnoq3u