• A White House official told CNN that since August 23, the Obama administration has had discussions with at least 93 senators and more than 350 House members regarding Syria. In addition to the president's efforts and his much-anticipated speech on Syria scheduled for Tuesday night, Vice President Joe Biden met with a group of House Republicans and House Democrats at the White House, the official said.
• Democratic House Leader Nancy Pelosi said the Russian plan has "given the president a victory" and said White House Chief of Staff Denis McDonough has told House Democrats, "if it is serious, if it is credible, if it is real, will be given every consideration." Democratic leaders say the plan doesn't take the wind out of the administration's efforts but "validates what the president is doing," Pelosi said.
• U.S. Rep. Brad Sherman met Tuesday with Sergey Kislyak, Russia's ambassador to the United States, to discuss Moscow's proposal to have Syria give up its chemical weapons, the California Democrat said. Sherman, a member of the House Foreign Affairs Committee, called the meeting informative and said he believes "the Russian proposal deserves very serious attention to develop the details needed to carry it out."
• A White House official said the feeling inside the White House is that, given the Russian proposal on Syria's chemical weapons, there is now less urgency for a vote on taking action against the country. However, White House officials believe their position has been strengthened since Syria embraced the Russian proposal to place the country's chemical weapons under international control. At this point, White House officials believe they can let diplomacy take its course, the official said.
• In meetings with Senate Democrats and Senate Republicans -- each lasting more than an hour -- President Obama asserted that U.S. intelligence assessments indicate that Syrian President Bashar al-Assad's government was responsible for a large-scale chemical weapons attack on August 21 outside Damascus, a White House official said.
While reiterating his position that a targeted military strike (without having troops set foot in Syria) was in the national security interests of the United States, the president said that his administration would work to pursue the diplomatic option put forward by Russia, which would involve Syria handing over its chemical weapons, the official said.
• Obama stressed during those meetings with U.S. senators the need to keep open the option of a military strike against Syria, said Sen. Tom Carper. According to the Delaware Democrat, Obama spoke for 10 to 12 minutes, then fielded questions from about 15 senators.
"If we don't keep that threat open," Carper said in summarizing the president, "they may very well walk away."
After the same meeting, Sen. Barbara Boxer, D-California, said she felt Obama is working towarda successful diplomatic resolution that would culminate in the documented destruction of the Syrian government's stockpile of chemical weapons.
• Kerry said Tuesday that the use of force "absolutely should not be off the table" in Congress despite the Russian proposal. But he told House lawmakers that when and how is up to Obama. "The Senate has made a decision to hold off to see if there are any legs in this Russia proposal," Kerry said, referring to the postponement of a procedural vote scheduled for Wednesday.
• Speaking later Tuesday in the Google+ Hangout, the secretary of state acknowledged that "some things" from the U.S. government have not gotten to opponents of Syria's al-Assad "as rapidly as one would have hoped." Without detailing what items were heading toward what he called "the moderate opposition," Kerry said "many of the items that people complained were not getting to them are now getting to them."
• Under a new resolution being proposed in the U.S. House of Representatives, Obama would have 30 days to work out a "credible plan" regarding Syria's chemical weapons before he'd be allowed to order strikes, Rep. Chris Van Hollen, D-Maryland, told CNN's Christiane Amanpour.
• Explaining the evolving timing of U.S. Senate votes on Syria in light of recent developments, Senate Majority Leader Harry Reid reiterated Tuesday, "It's important that we do this well, not quickly." The Nevada Democrat added that "the credible threat of our doing something about this (chemical weapons) attack is going to remain."
Reid's comments came after Obama asked Senate Democrats to delay voting on authorizing military action in Syria while the diplomatic process works itself out, according to senators in the meeting. The president "asked for some time to work things out -- a matter of days into next week," Sen. Dick Durbin said.
• Senate Majority Leader Harry Reid announced Tuesday evening that he is canceling a briefing on Syria that had been planned for Wednesday for all senators, explaining that there are just too many moving targets at the moment.
• Sen. Joe Manchin -- a West Virginia Democrat who last week had pushed an initiative to put off military action while demanding Syria signs an international convention against chemical weapons -- said Tuesday that he is "encouraged" that Syria's government has decided to sign on to such an agreement. "I have said from the start that being a superpower means more than super-military might; it means super-diplomacy and super-restraint," Manchin said in a statement.
• A bipartisan group of U.S. senators is working on an alternative resolution that would set key benchmarks to be met in order to avoid a military strike against Syria, according to a source familiar with the talks.
• Testifying before the House Armed Services Committee on Tuesday, Kerry told lawmakers that a "credible threat of force" in recent weeks has for the "first time" prompted the Syrian regime "to even acknowledge that they have a chemical weapons arsenal." He added that a Russian proposal to turn over Syria's chemical weapons stockpile can't be a process for "delay" or "avoidance."
• Kerry also warned the committee that Iran, a close ally of Syria, "looms out there with its nuclear program." "They are watching what we do here. If we choose not to act, we will be sending a message to Iran of American ambivalence, American weakness," he said.
• U.S. Rep. Adam Kinzinger, an Illinois Republican on the House Foreign Affairs Committee, told CNN's Jake Tapper on Tuesday that he believes there needs to be a detailed timeline for Syria to hand over its chemical weapons. Referring to the Moscow-led efforts calling for such a transfer in the face of threatened U.S.-led military strikes in Syria, Kinzinger said, "It's important to understand that the Russians may be trying to stall here."
• The top-ranking Republican in the Senate said Tuesday that he will vote against authorizing military action against Syria. "A vital national security risk is clearly not at play. There are just too many unanswered questions about our long-term strategy in Syria," Sen. Mitch McConnell of Kentucky said in a speech on the floor of the Senate.
• On CNN's "New Day," Sen. John McCain upbraided the Obama administration's discussions of Syria. "There's a degree of incoherence that I have never seen the likes of," the Arizona Republican said. He noted that Kerry said any strike on Syria would be "unbelievably small." "What does that mean?" McCain asked. "We still haven't determined what the goal of these military strikes are."
• Frederic Hof, who served as a special adviser to Obama on Syria during its ongoing civil war, told CNN's Christiane Amanpour that he's a "bit skeptical" of the Russian proposal on chemical weapons, further pointing out that Monday was the first day Syria's government ever admitted to having such an arsenal.
In his speech Tuesday night, "The president absolutely has to get across (the point) that diplomacy is not possible without the credible use of force remaining on the table," said Hof, now a senior fellow with the Atlantic Council think tank. "Absent that, the Russian proposal will go away."
• While U.S. forces are in position and capable of striking immediately, the Pentagon needs more guidance from President Barack Obama about time frames for a possible strike against Syria, a senior U.S. military official said.