WASHINGTON, District of Columbia - After staring deep into his political soul over Syria, Barack Obama blinked.
Stunning his advisors, his opponents, and the rest of the world, Obama chose to rein in his own power, and asked Congress to authorise a military intervention he had been set to wage alone.
Senior aides say Obama took the momentous decision alone on Friday evening, then explained it in a heart to heart with his chief of staff Denis McDonough.
Before then, the spin had been that Obama had the legal and moral right to strike President Bashar al-Assad's regime to punish a horrific chemical weapons attack.
But Obama was out on a limb - potentially defying public opinion and the United Nations, deserted by America's best friend, Britain.
By stopping at the brink, Obama will face claims he is weak, does not make good on his threats and presides over a feckless foreign policy.
But acting alone would have repudiated one of the central principles that got him elected - the idea that imperial presidents should not plunge into foreign quagmires with their authority unchecked.
In 2007, Obama, a former constitutional law professor criticised ex-president George W. Bush for endless, unaccountable wars.
"The President does not have power under the Constitution to unilaterally authorise a military attack in a situation that does not involve stopping an actual or imminent threat to the nation," he told The Boston Globe.