Anchored by Jake Tapper, The Lead airs at 4 p.m. ET on CNN.
Continuing coverage of Malaysia Airlines Flight 17. Plus, the latest on Mideast tensions.
President Barack Obama was on Capitol Hill, trying to sway lawmakers to back military action in Syria if a diplomatic solution fizzles.
Obama also reportedly asked for more time to see a so-called third option potentially take shape, before Congress takes up a vote on military action that the president may lose. The third option is a proposal from Russia to disarm Syria of its chemical weapons
A majority of the House remains undecided, but the "No's" seem to have the momentum, just hours before the president addresses the nation.
Republican Congressman Adam Kinzinger and Democratic Congresswoman Tulsi Gabbard are both members of the House Foreign Affairs Committee, and have both served in the United States military; Gabbard is against military action, while Kinzinger backs the president's plan.
Kinzinger is wary of Russia's proposal, saying the country may be trying to stall and has been a long-time ally and protector of Syrian President Bashar al-Assad.
"But look, we have a responsibility now to see if we can disarm the Syrians through peaceful methods, and I hope it works," said Kinzinger.
Gabbard said disarming Syria "is the option, in particular, the Americans have been looking for."
"The president moving forward with this, delaying the Senate vote, is a positive development. And Russia calling an emergency U.N. Security Council meeting today to start to work through the resolution is exactly the path that we need to be taking forward," said Gabbard.
But Kinzinger said Russia's proposal is only on the table because the U.S. threatened to strike.
"The reason we're here with the Russians potentially, and the U.N. potentially making this breakthrough is because there was a threat of force, because the United States was serious about making the cost of using chemical weapons far exceed any benefit gain," said Kinzinger.
"That is a huge testimony, frankly, to saying in some cases a strike like this is necessary. That's why I supported it and that's why if there's stalling that goes on, I support taking action still," said Kinzinger.
Gabbard said the effect of a threat from the U.S. is debatable, saying pressure from the international community has played a factor in changing the conversation on Syria. A U.S. military strike, she added, will not meet Obama's objective of degrading and deterring Assad from using chemical weapons again.
"The opposite effect could occur. We could see a very limited strike, unbelievably small as Secretary Kerry said yesterday, that does not meet that intent, and further emboldens other leaders to say this is actually a weak response that could further embolden the opposition forces," said Gabbard.
But if Obama sets a red line on the use of chemical weapons and does not follow through with punishment, that could hurt America's credibility.
"Would it not be potentially irresponsible to take action against Syria just for the sake of saying we took action against Syria, when that action could lead to something far worse?" said Gabbard.
A U.S. strike could lead to a regional conflict, a weakened Syrian regime, and strengthened opposition forces made up of multiple terrorist factions who could hurt the United States, says Gabbard.
"It is our responsibility to exercise moral courage, to find that right solution. It's not a question of a military strike, or complete and total inaction," said Gabbard.
Secretary of State John Kerry said Tuesday, "We're not asking to go into Syria. I don't see any route by which we slide in to go into Syria. I don't see the slippery slope. People say you're going to get dragged in. I do not see that."
"I see a very punishing strike coming to Syria for doing what they shouldn't have done," said Kinzinger.
"America's credibility and not just the credibility of the president, the whole United States of America and what we have done for decades is at risk if we don't follow through. I hope they're disarmed through peaceful means. If they're not, we need to be ready to attack," said Kinzinger.
Kinzinger further dismissed the idea of a slippery slope, pointing to Israel who has made limited strikes on Syria.
"It didn't start World War III. A very punishing strike by the United States saying, 'You will not gas your own people,' will I think be very effective in deterring them from doing this in the future," said Kinzinger.