Sen. John McCainJohn Sidney McCainRubio asks Army to kick out West Point grad with pro-communist posts The VA's woes cannot be pinned on any singular administration Overnight Defense: Mattis offers support for Iran deal | McCain blocks nominees over Afghanistan strategy | Trump, Tillerson spilt raises new questions about N. Korea policy MORE (R-Ariz.) called for immediate U.S. action in Iraq on Wednesday.

“There is a need for immediate action,” McCain said on the Senate floor. “The worst option is to do nothing.”

An extremist Islamic group, Islamic State in Iraq and Syria, has taken over several major Iraqi cities, advancing to the outskirts of Baghdad. The administration has sent hundreds of troops to protect the U.S. Embassy in Baghdad. 

McCain said that if the administration fails to act, ISIS would pose a direct threat to the United States.

Republicans have blamed Obama, saying he ended the Iraq War too early.

McCain said political reconciliation between Islamic groups in Iraq is key to peace, but said that can’t be a “prerequisite for military action.”

McCain called for U.S. airstrikes in the region, if for nothing else than boosting morale.

Earlier Wednesday, Senate Majority Leader Harry Reid (D-Nev.) said this is an Iraq civil war that the United States should not get involved in.

But McCain said Reid was wrong because ISIS is also present in Syria and other Middle Eastern countries.

“This is not an Iraqi conflict,” McCain said. “This is an Iraqi-Syrian conflict now.”