Transcript for Syrian Chemical Weapons Images Used to Justify US Strike
Our thanks to you. Turn now to the white house, stemming the case to attack syria. Senators being shown horrifying images of the chemical weapons attack they believe was carried about by the assad government. The president is trying to persuade the american people that military action is the solution. Jeff swrelny has the story from the white house. These are some of the most gruesome and disturbing videos we have seen yet. Reporter: Good morning. You're right, they are gruesome and graphic. But these images are part of a central case that president obama is trying to make to overcome a growing died of public opinion as he tries to make the case for why military strikes against syria are necessary. Obama, hands off syria. Reporter: As anti-war protesters rallied outside the white house and across the didn't -- the president is calling lawmakers. The vice president is preparing to host skeptical republicans for sunday night dinner, and secretary of state john kerry is pressing hard with war-weary european allies. This is not the time to be silent spectators to slaughter. Reporter: Overnight, abc news obtained what is now at the heart of the administration's case to congress, a series of 13 videos senators viewed in a classified briefing last week. The images are too gruesome to watch in full. The syrian civilians, many are children. They are the same heartbreaking images that prompted this response from senator dianne feinstein when asked why so many americans oppose military action. They don't know what I know. They haven't heard what I heard. Reporter: The administration hoping those images have the same effect on the american people. It's a tough sell for president obama, the toughest of his presidency. He will sit down for interviews on monday, followed by an address to the american people on tuesday. Now the white house is getting heaven, david petraeus, the former cia director is calling for strong action against the syrian regime. The white house hopes that helps win over sop republicans. As the vote comes as early as wednesday, our survey of lawmakers shows that the white house needs a dozen more senators on their side, and in the house, the scepticism is deeper. A lot of work. A tense weekend kicking off a tense week for the president. Thanks to you. Tune in for diane sawyer's interview on world news ahead of his address on tuesday. George, with the big push tomorrow and the address to the nation tuesday night, how would you place the success of odds? If the vote were today, 4e8d lose. He does have a decent chance of getting the votes in the senate starting this week to pass it through. And the white house hope is that will build momentum to halt the erosion in the house and get numbers up, particularly among democrats. Another key event could be, and the french are waiting for this, the u.N. Inspectors next weekend on the chemical weapons in syria. If it were today, no question, he would luose. If he doesn't get the votes, will he still strike? It's a lose, lose situation. It would be the first time it happened to a president, losing the vote on military force. It's all but impossible for the president to go forward in the face of no votes. Listen to what he said friday night in russia. It's not a political ploy or symbolism. He could not say that it posed a threat to the united states. In the face of that, I don't see how he could go forward. Is it possible he gets a yes vote in the senate and the house doesn't vote? Maybe that's the way out, unclear. What are the stakes for his presidency and his ability to get things done the rest of the term if he fails? It's hard to believe a month ago this wasn't contemplated. Now the most important -- if he loses, damage american's credibility on the world stage and complicate everything in the final three and a half years. And george is going to have much more on "this week" right here on abc. Thanks again.
This transcript has been automatically generated and may not be 100% accurate.