Anchored by Jake Tapper, The Lead airs at 4 p.m. ET on CNN.
The latest news on the crisis in Ukraine, plus a look at the technology aiding in search for Flight 370.
President Barack Obama argued Wednesday that any red line he drew against chemical weapons use in Syria was based on international norms, saying: "I didn't set a red line. The world set a red line."
One year ago, in Agusut 2012, Obama said, "A red line for us is we start seeing a whole bunch of chemical weapons moving around or being utilized ... That would change my calculus."
"What he's trying to do is depersonalize this. He's come under a lot of criticism. People are saying it's your red line, you set it, now we have to take military strikes so you don't lose your credibility," said CNN's chief political analyst Gloria Borger.
"In fact, it is his red line. He drew the red line, he spoke about it – the two are not mutually exclusive. It could be the world's and his. He is going to Congress asking for this military action. I think he owns the request," said Borger. "What he was trying to do is say to Republicans in particular, 'You don't need to do this for me. Take me out of this.'"
Congress and most countries in the western world have ratified a ban on chemical weapons.
"What you're going to start to see is ... some reminders about the fact that some of the senators, even in this committee today who voted no, did support the Syria Accountability Act before," said CNN chief congressional correspondent Dana Bash.
Lawmakers will be questioned about contradicting themselves, especially if the vote is tremendously tight, said Bash.