Sen. Ted Cruz, R-Texas (center left) is a Tea Party favorite, whom observers count as a possible 2016 presidential candidate. He voted against President Obama's plan to fight the Islamic State. J. Scott Applewhite/AP hide caption

itoggle caption J. Scott Applewhite/AP

President Obama addresses the nation from the Cross Hall in the White House on Sept. 10. Obama ordered the United States into a broad military campaign to degrade and ultimately destroy militants in two volatile Middle East nations, authorizing airstrikes inside Syria for the first time, as well as an expansion of strikes in Iraq. Saul Loeb/AP hide caption

itoggle caption Saul Loeb/AP

President Obama addresses the nation from Cross Hall in the White House on Wednesday. Opening a new military front in the Middle East, Obama authorized U.S. airstrikes inside Syria for the first time, along with expanded strikes in Iraq as part of a broad mission to root out violent Islamic State militants. Saul Loeb/AP hide caption

itoggle caption Saul Loeb/AP

Members of the Senate and the House of Representatives return to work at the Capitol this week after a five-week vacation. They must get to work on a continuing resolution to extend funding for government agencies to prevent a government shutdown. J. Scott Applewhite/AP hide caption

itoggle caption J. Scott Applewhite/AP