Why did Obama flip flop on the War Powers Act?

Why did Obama flip flop on the War Powers Act?

Obama In 2007: Congress Should Stand Up To White House On War Powers Act

WASHINGTON –- President Barack Obama spoke passionately in 2007 about the need for Congress to challenge the Bush administration over violating the War Powers Act -- the very charge he is now facing from lawmakers in both parties over U.S. military involvement in Libya. Back when Obama was a senator, he talked tough on the need for Congress to find "a backbone" and keep then-President George W. Bush in check regarding the legality of the Iraq War.