ST. PETERSBURG, Russia — After two days of intense lobbying, President Obama left a summit with world leaders Friday with some expressions of support for a strong U.S. response to Syria's alleged use of chemical weapons, but well short of an international coalition that might help persuade reluctant lawmakers. 
 
 The president had hoped to use the meeting of the Group of 20 nations to build pressure on Congress as it considers whether to authorize missile strikes against Syrian President Bashar Assad's government. 
 
 Before leaving for Washington, Obama said at a news conference that he will make his case in an address from the White House on Tuesday, an acknowledgment that his plans remain divisive both abroad and at home. 
 
 "This is not something that I think a lot of folks around the world, you know, find an appetizing set of choices," he said. "But the question is, do these norms mean something? And if we're not acting, what does that say?" 
 
 The president had to settle for a carefully worded statement backed by representatives of 10 countries that said Assad should be held accountable for an alleged nerve gas attack on the Damascus suburbs two weeks ago, but did not explicitly support military action or promise participation. Among the leaders who did not endorse the statement was the summit's host, Russian President Vladimir Putin, who is Assad's closest ally. 
 
 Obama and Putin pulled up two chairs in a corner and talked for more than 20 minutes Friday, almost entirely about Syria. The leaders have exchanged harsh words, but Putin called the talk "friendly" and Obama said it was "candid and constructive." But it did not break their impasse over how to respond to the suspected chemical weapons attack or how to end the 21/2-year-old Syrian civil war. 
 
 "We both remained unconvinced by each other's opinion," Putin said at a news conference. "But there is a dialogue. We hear each other, we understand arguments, but we don't agree with them." 
 
 Putin added that Russia will continue to supply weapons to Assad in his battle against the rebel opposition. Local news reports said three Russian ships and possibly a fourth were headed to the eastern Mediterranean, where the United States has four guided missile destroyers and an amphibious ship with 300 Marines. 
 
 At a dinner that stretched into morning hours Friday, world leaders vigorously debated Obama's plan, with many saying the president should wait for the United Nations to complete a report on the Aug. 21 attack and sanction a response. Obama argued that the U.N. Security Council was paralyzed by disagreement. Russia and China, which have veto power, have blocked efforts at the Security Council to put pressure on Assad. 
 
 Obama's plan for what he stresses will be "limited and not open-ended" strikes also remains unpopular in the United States. The statement and the heated discussion was a reminder of what Obama has called "a heavy lift" as he seeks to sell lawmakers and the American public on the need for a military response. 
 
 Jon B. Alterman, the director of the Middle East Program at the Center for Strategic and International Studies, said the problem for Obama isn't whether he has international support but American support. "The people who matter right now are Americans," he said. "If he can't convince them, it's catastrophic for his presidency." 
 
 The Senate could take the first vote on the issue as soon as Wednesday, but the House should "expect a robust debate" and a vote in the "next two weeks," Majority Leader Eric Cantor (R-Va.) said. 
 
 Although the Senate Foreign Relations Committee quickly approved a resolution this week, the already challenging politics have since become more complicated. Sen. Joe Manchin III (D-W.Va.), who opposes the resolution, was consulting his colleagues on a proposal for a nonmilitary response. 
 
 In the House, Rep. Chris Van Hollen (D-Md.) said the Senate resolution, which aims to shift the momentum in the civil war toward the opposition, "opens up a Pandora's box." "I think the administration runs an incredible risk, if they try to placate those who want to expand American military intervention in Syria, because they risk losing support of the overwhelming majority of members," he said after meeting with Vice President Joe Biden. 
 
 The Obama administration had resisted intervention in the war, but switched course after the alleged chemical weapons attack, which U.S. intelligence agencies have concluded killed more than 1,400 people. 
 
 On Friday, Obama compared his bid for action to humanitarian intervention in Kosovo in 1999 and the U.S. failure to stop the genocide in Rwanda in 1994. He cast the international division as the result of war-weary leaders "rationalizing not making tough choices." The United States alone, he said, shoulders the burden of enforcing international agreements on human rights and chemical warfare. 
 
 "There are times where we have to make hard choices if we're going to stand up for the things that we care about. And I believe that this is one of those times," Obama said. 
 
 But Obama did not persuade a single ally to endorse a specific action. Immediately after he spoke, the White House released the joint statement from Australia, Britain, Canada, France, Italy, Japan, South Korea, Saudi Arabia, Spain and Turkey, as well as the United States. It found that evidence "clearly points" to Assad's government as responsible for the attack, called for a "strong international response to this grave violation of the world's rules and conscience" and asserted that "the world cannot wait for endless failed processes." 
 
 The statement did not specifically endorse military action, but concluded, "We support efforts undertaken by the United States and other countries to reinforce the prohibition on the use of chemical weapons." 
 
 A White House official, however, said there was no question what that implied. "The president has been very clear about how he intends to do that with tailored military action," a senior administration official said. 
 
 Still, the support was largely symbolic. The British Parliament has voted against participation in a military campaign. French President Francois Hollande, who offered the earliest support for Obama's plan, said Friday that his country will not engage in any action until after U.N. inspectors issue their report on the attack. 
 
 Obama's last-minute decision to ask Congress to vote to approve the use of force gave world leaders little reason to risk supporting a mission that may not occur. The president has insisted that he does not need congressional authorization, but reiterated Friday that it would make a U.S. response "more effective and stronger." 
 
 Obama would not say whether he will launch missiles even if he loses the vote. Pressed on the issue, Obama was blunt. "You're not getting a direct response," he said. "I'm not going to engage in parlor games." 
 
 In his absence from Washington on Friday, Biden, Secretary of State John F. Kerry and Chief of Staff Denis McDonough worked the phones; U.S. officials briefed members of Congress; and Samantha Power, the U.S. ambassador to the United Nations, gave a speech at a think tank, arguing, "The use of limited military force can strengthen our diplomacy and energize the efforts by the U.N. and others." 
 
 When Obama returns to Washington, he will oversee one of the most momentous lobbying efforts in his tenure. He promised that his administration would "systematically" reach out to every member of Congress. 
 
 "I do consider it part of my job to help make the case and to explain to the American people exactly why I think this is the right thing to do," he said, acknowledging that "it's conceivable that, at the end of the day, I don't persuade a majority of the American people that it's the right thing to do." 
 
 kathleen.hennessey@latimes.com 
 
 sergei.loiko@latimes.com 
 
 Hennessey reported from St. Petersburg and Loiko from Moscow. Times staff writers Michael A. Memoli, Christi Parsons and Paul Richter in Washington contributed to this report. ||||| WASHINGTON President Barack Obama told his war-weary country on Saturday that America needs to use limited military force in Syria to deter future chemical weapons attacks, but said he did not want to enter into another costly and protracted war. 
 
 "This would not be another Iraq or Afghanistan," Obama said in his weekly radio and internet address, previewing arguments he will make in a nationally televised address on Tuesday. 
 
 "Any action we take would be limited, both in time and scope - designed to deter the Syrian government from gassing its own people again and degrade its ability to do so," Obama said. 
 
 A week ago, Obama said he felt limited strikes in Syria were needed, but added he wanted to ask Congress to authorize the use of military force. 
 
 Neither Democratic nor Republican lawmakers have been enthused about the prospect, partly because Americans strongly oppose getting involved in another Middle Eastern conflict. 
 
 A Reuters/Ipsos poll on Tuesday said 56 percent of Americans believed the United States should not intervene, while only 19 percent supported action. 
 
 "I know that the American people are weary after a decade of war, even as the war in Iraq has ended, and the war in Afghanistan is winding down. That's why we're not putting our troops in the middle of somebody else's war," Obama said in his recorded address. 
 
 Obama and his top officials plan an intensive lobbying effort on Capitol Hill next week, scheduling meetings with undecided lawmakers. 
 
 Obama said failing to respond to the August 21 attack that Washington blames on President Bashar al-Assad's government and that killed hundreds of children and more than 1,400 people in total, would threaten U.S. national security by increasing the chance of future chemical attacks from the Syrian government, terrorist groups, or other nations. 
 
 "We are the United States of America. We cannot turn a blind eye to images like the ones we've seen out of Syria," he said. 
 
 (Reporting by Roberta Rampton; Editing by Peter Cooney)
– President Obama didn't exactly return from the G20 summit with a ringing international endorsement to take action against Syria, but he continued making his case before his own nation this morning via his weekly radio address. Obama hit familiar themes, ones he will surely revisit in his speech to the nation Tuesday night, reports Reuters. "This would not be another Iraq or Afghanistan." "Any action we take would be limited, both in time and scope—designed to deter the Syrian government from gassing its own people again and degrade its ability to do so." "I know that the American people are weary after a decade of war, even as the war in Iraq has ended, and the war in Afghanistan is winding down. That's why we're not putting our troops in the middle of somebody else's war." As for the G20 summit: Obama got the backing of 10 countries for a statement that says Bashar al-Assad should be held accountable for using chemical weapons, but the statement pointedly fell short of calling for military action, notes the Los Angeles Times, which concludes that the president "fell well short of an international coalition that might help persuade reluctant lawmakers."