As President Obama has made the case for U.S. military intervention in Syria, his most starkly emotional appeal has focused on images of dead and wounded kids.

He pointed to such imagery in his address to the nation Tuesday night, describing “a father clutching his dead children, imploring them to get up and walk” after an alleged sarin gas attack that killed more than 1,400 people, including hundreds of children.

“On that terrible night, the world saw in gruesome detail the terrible nature of chemical weapons,” the president said. “I ask you to reconcile your belief in freedom and dignity for all people with those images of children writhing in pain and going still on a cold hospital floor.”

Obama’s raw language was in many ways similar to the words he used in the wake of a mass shooting in Newtown, Conn., last winter, and was aimed at stirring a nation’s collective conscience to action in a faraway place.

So far, however, there is scant evidence that the American public or Congress has been swayed by the graphic videos, which were recorded in the neighborhoods near Damascus where the Aug. 21 attacks were allegedly carried out.

During the president's speech Tuesday night, he laid out a number of contradictory arguments. Chris Cillizza asks The Post's Karen Tumulty and Scott Wilson to cut through the rhetoric. (The Washington Post)

The administration has struggled to make the case that the alleged use of chemical weapons by Syrian President Bashar al-Assad on his own people has constituted such a horrifying escalation of the country’s civil war that a U.S military intervention is required.

In a Washington Post/ABC News poll last week, 64 percent opposed U.S. military action in Syria.

There are many reasons why the public and lawmakers may be unprepared to support a U.S. attack on Syrian targets, including war fatigue after Afghanistan and Iraq and a lack of clarity from the administration about its goals. But some experts said another factor might be at play: The images, while gruesome and disturbing, do not immediately produce a clear narrative.

Images of dead bodies or men gasping for air and convulsing may produce a horrified reaction, but they do not necessarily explain to a viewer what happened or why, said Scott Sigmund Gartner, a scholar at Penn State University who has studied the effect of war imagery on the public.

“The images that are the most powerful tell a story that is understandable without captions, without additional explanation,” Gartner said. “The images I’ve seen in the media are terrible; they are horrific. But they do not tell a story about the role of chemical weapons — and it’s unfair to even ask that of an image because with chemical weapons, most of the time there’s nothing to see.”

Obama, briefed daily by his national security team, “sees the photos and is essentially writing his own captions,” Gartner added. “The public sees them without his feeling of responsibility.”

The administration has tried to alter that dynamic. National security adviser Susan E. Rice opened a speech on Syria at a think tank with her personal reflections as a parent: “I cannot look at those pictures, those little children laying on the ground, their eyes glassy, their bodies twitching, and not think of my own two kids.”

Over the weekend, the administration leaked a collection of 13 videos from Syria to CNN’s Jake Tapper and other journalists. The videos showed the aftermath of the attacks and reportedly were authenticated by the CIA. They were among more than 100 videos put online by Syrians sympathetic to opposition forces, and they were shown to senators last week in a classified briefing.

The videos, in some cases shaky and dark, show scenes of chaos, with people convulsing and foaming at the mouth, and close-ups of the victims’ eyes. In the final video, a man holds the limp body of a small child, whose head is bobbing backward.

“It is a very upsetting and disturbing image,” Tapper told viewers, adding that “these videos do not show, do not prove who carried this out.”

CNN’s online package on the videos has drawn more than 8,400 viewer comments and 23,000 links on Facebook.

Charles Blair, of the Federation of American Scientists, said humans are “hard-wired” to be frightened by poisons and gases. But on Syria, he said, the videos lack raw emotional power compared to bloodier photos and videos that the public has seen from other war zones.

During the creation of the atomic bomb, scientists watching a test blast in the desert “were uninspired by it,” Blair said. “It was not as large as they thought, and people were underwhelmed by the power. They were a faraway series of blasts. This is sort of the same thing.”

Richard Price, a professor of political science at the University of British Columbia, is the author of “The Chemical Weapons Taboo,” which traces the history of chemical weapons from World War I through Nazi concentration camps and to an international agreement forbidding such weapons in 1997.

In his study, Price found that contrary to conventional wisdom, people did not immediately have a more visceral reaction to the damage inflicted by chemical weapons than from others.

“It’s not that people do not have a reaction to the horror; they do,” Price said. “But is it any different from other forms of mass casualties?”

During an online forum hosted by Google+ on Tuesday, Andrew Beiter, an eighth-grade social studies teacher from Springville, N.Y., asked Secretary of State John F. Kerry why the United States wanted to intervene over chemical weapons when it had not done so in response to more than 100,000 deaths from conventional fighting.

“While everyone gets the major issues associated with the use of chemical weapons,” Beiter said, “why is it that there’s such a concern now?”

During his address Tuesday, Obama stepped up the vivid rhetoric, tying the attack in Syria to the Holocaust. But even his allies are finding it tough to convince a skeptical public.

After meeting with the president last week, House Minority Leader Nancy Pelosi (D-Calif.) told reporters about a discussion with her 5-year-old grandson, who was arguing against war.

“Well, I generally agree with that, but you know, they have killed hundreds of children there,” Pelosi told him.

“Were these children in the United States?” the boy responded.

“And I said, ‘No, but they’re children wherever they are,’ ” Pelosi said.