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On the day U.S. senators were supposed to start voting on authorizing force against Syria, Secretary of State John Kerry will instead be on his way to Geneva to talk peace with his Russian counterpart to discuss a so-called third option – disarming Syria of its stockpile of chemical weapons.
"President Obama will take a hard look at it. But it has to be swift. It has to be real. It has to be verifiable. It cannot be a delaying tactic," Kerry said of Russia's diplomatic proposal.
Turning the proposal into reality is already facing its first hurdles. Russia said it would be "unacceptable" to blame the Syrian regime for last month's chemical attack, and insists any resolution must come with a renunciation of force by the U.S.
"You can't really ask Syria, or any other country, to disarm unilaterally while military action against it is being contemplated," Russian President Vladimir Putin said.
Undeterred, U.S. officials said they will still seek a force authorization, and that will only strengthen diplomacy.
"Nothing focuses the mind like the prospect of a hanging," said Kerry.
Looming over negotiations is deep distrust that the Syrians are truly committed to giving up their chemical weapons for good, and that Russia is committed to forcing them.
"When you see the plane loads of Russian arms flying into Damascus on a daily basis, tons and tons, when you see the Russian veto time after time of any resolution in the (U.N.) Security Council, it gives us ample reason to be skeptical," Republican Sen. John McCain said.
The practical obstacles to ridding Syria of chemical weapons may be even more imposing than the diplomatic hurdles.
Syria has 1,000 tons of numerous chemical agents, including ingredients for mustard, sarin and VX gas in six known sites, and many more unknown. Those stockpiles are now likely dispersed and hidden, as the U.S. has considered strikes.
All this, in a country in the middle of a civil war.
"It will take weeks to get inspectors there to conduct an initial inventory, to secure the sites will probably take several months," said Joe Cirincione, president of Ploughshares Fund, a global security foundation that seeks to make progress toward a world free of nuclear weapons. "Destroying the weapons - that will take years."
All these estimates do not account for the fact that Syria is also a country at war, where the difficulty of even the simplest tasks is magnified: Taking inventory of weapons, transporting them, destroying them, and keeping inspectors safe. These are some of the questions Secretary Kerry and his team, now including Pentagon WMD experts, will be addressing and testing with their Russian counterparts in Geneva.