Countdown to the Showdown Between Obama and Putin They have moved forward. Now we head overseas to where two of the world's most powerful leaders are heading for a dual on the world's stage. President obama and vladimir putin taking opposite sides. In 24 hours they will be face to face. Jonathan karl is traveling to the summit of major world leaders tonight. Reporter: Shortly after landing in sweden today, president obama said responding to syria's chemical weapons attack is now more than just his leadership. My credibility is not on the line, the international community's is on the line and america an congress. Reporter: He pointed out that chemical weapons like those used in syria have been banned by national law for a century. I didn't set a red line, the world did. Reporter: But on this eve, putin is once again standing in opposition today accusing secretary of state john kerry of lying about syria. And in a rare interview with western media, suggesting it was syrian rebels, not the government, who used chemical weapons. Putin denied having a frosty relationship with president obama but he added your humble servant hasn't been elected by the people of russia to be pleasant to someone either. Back in washington, the white house won a narrow victory today when the senate foreign relays committee approved the authority to attack syria. Five republicans and two democrats voted no, suggesting a tough battle ahead. I see a horrible tragedy but I don't see that our involvement will lesson the tragedy. Reporter: The president will see putin tomorrow for the first time since russia granted asylum to edward snowden. The two will undoubtedly exchange a few words but there are no plans for a one on one meeting and nobody expects any break through on syria.