Democrats stood firm behind President Obama’s decision against military intervention in Iraq on Friday, asserting that the upheaval taking place there is not being caused by an absence of U.S. troops.

Some Republican lawmakers have faulted Obama for failing to prevent rebel fighters from the Islamic State of Iraq and Syria (ISIS) from seizing territory in northern and western Iraq from the government of Prime Minister Nouri al-Maliki. The intensified fighting threatens to completely destabilize the country, with potentially dire political consequences in the region.

But Democrats say the current violence was not a result of Obama’s decision to withdraw U.S. forces in 2011. They instead blame Maliki for refusing an agreement that would have kept U.S. forces in the country. The outburst of fighting, they say, is the result of the Iraqi government’s failure to quell sectarian tensions between Maliki’s Shiite-dominated government and minority Sunni and Kurdish populations.

“What’s happening in Iraq today is an absolute tragedy, but it is much more a consequence of our invasion than our withdrawal,” Sen. Chris Murphy (D-Conn.) said in an interview. “The blame for what’s happening right now is squarely at Maliki’s feet. This is not a responsibility of the United States.”

Murphy arrived in Washington as a House lawmaker in 2007 as Congress prepared to debate President George W. Bush’s proposed troop “surge” to help end the growing conflict. Murphy said Friday that his vote against the surge contributed in no way to the fresh trouble there.

Rep. Adam B. Schiff (D-Calif.) was a junior member of the Democratic caucus when party leaders began calling for a withdrawal from Iraq. Now a senior member of the House Intelligence Committee, he said Friday that Obama had no choice but to withdraw when Maliki refused to ensure U.S. troops legal immunity as part of an “status of forces” agreement.

“Whether we kept a certain number of troops there or pulled out completely, if we can’t get the Maliki government to include a large segment of its population in its security forces and protection, then the small amount of forces that we would have left there might have slowed this day, but they wouldn’t have prevented it altogether,” Schiff said.

House Minority Leader Nancy Pelosi (D-Calif.) on Friday applauded Obama’s decision. It was eight years ago this summer that she and Senate Democrats made the worsening situation in Iraq the centerpiece of their successful campaign to take control of Congress. Once in control, Democratic leaders sparred with Bush on Iraq for most of the final two years of his presidency.

Their position was further buoyed when Obama won the 2008 presidential election in part by highlighting his opposition to the Iraq war. His decision to withdraw U.S. forces at the end of 2011 was so popular that even a majority of Republicans backed the move.

The war remains deeply unpopular with Americans. In March 2013, 38 percent said the costs of the war were worth the effort; 58 percent said they were not.

The war had been especially unpopular among Democrats almost from its beginning, while Republicans were more supportive to start. A decision by Obama to use military force in Iraq is unlikely to suddenly find greater favor among either Democrats or Republicans.

That’s why GOP lawmakers have largely avoided talk of redeploying ground troops. Instead, some are calling for the quick use of other military options.

On Friday, Sens. John McCain (R-Ariz.) and Lindsey O. Graham (R-S.C.), Obama’s fiercest GOP critics on issues of foreign policy, called the situation an “urgent security problem” and said that U.S. airstrikes and other military and intelligence actions would be the only way to stop the ISIS.

Others agreed.

“We shouldn’t have boots on the ground, but we need to be hitting these columns of terrorists marching on Baghdad with drones now,” House Foreign Affairs Committee Chairman Edward R. Royce (R-Calif.) said in a statement Friday. Rep. Michael McCaul (R-Texas), who chairs the House Homeland Security Committee, said that Obama’s decision to take the next several days to review options means the administration “is wringing its hands as Baghdad is about to fall. This is not leadership.”

If Obama chooses to take limited military action, he could face opposition from dozens of Democrats who opposed military action against the government of Syrian President Bashar al-Assad last summer, a factor that contributed to the president’s decision not to use military force. Nearly a year later, Democrats said that congressional consultation will be needed again.

“The White House has got to come to us very quickly” with options, Sen. Timothy M. Kaine (D-Va.) said Thursday before Obama’s remarks. “They’re working around the clock trying to figure that out, but they need to now bring that to us.”

Murphy said he believed that an existing authorization for the use of military force in Iraq would not apply if Obama seeks to target members of the ISIS.

“If he’s contemplating any new sustained military action in Iraq, I would argue that he needs a new authorization,” he said.

Rep. Tulsi Gabbard (D-Hawaii), an Army veteran of the war in Iraq, said Friday that Obama should consult Congress, but that she would oppose using force.

“It is not within the best interest of the United States to insert ourselves in the middle of his religious sectarian war,” she said. “For those who are calling for airstrikes, for those who are calling for drone strikes, my question is, what will that actually accomplish? What is the goal?”

Aaron Blake and Alice Crites contributed to this report.