Updated 1:43 p.m.

As the full Congress returns to Washington Monday, progressive groups are again challenging the White House’s case for a strike against Syria.

MoveOn.org released an ad urging lawmakers to avoid authorizing the use of military force against Syrian President Bashar al-Assad’s regime. A narrator says, “Don’t lead us down this road again,” while images and statistics from the wars in Iraq and Afghanistan are displayed in the background of the 30-second commercial, titled “Not Again.”

The group created the ad after discovering that more than 70% of its 8 million members “firmly opposed” the strike, said Anna Galland, executive director of MoveOn. They made thousands of calls to congressional leaders last week urging them to find alternative solutions in responding to Assad’s alleged use of chemical weapons.

There is “deep concern that this is going to lead us deeper and deeper into yet another war halfway around the world with a country that poses no direct threat to our safety and security,” Galland told MSNBC. “This could be a slippery slope to a longer-term engagement, and our members don’t have the appetite for that; we don’t think the American public has an appetite for that.”

Progressive organizations, including MoveOn.org Civic Action, Win Without War, Progressive Change Campaign Committee (PCCC), and USAction united Monday for a national day of action. A vigil was held in the morning near the perimeter of the Capitol, and more than 150 candlelight vigils were planned around the country with the same message: “Don’t bomb Syria.” One group distributed leaflets and spoke with leaders as they returned from their August recess.

The commercial is the group’s first televised effort to try and influence Congress. It is set to air on MSNBC throughout the week.

President Obama has made clear his belief that Assad ordered the use of chemical weapons against Syrian citizens on Aug. 21, consequently killing more than 1,400 people. But the legacy of Iraq overshadows the country’s support for strikes in Syria.

Obama has gained support from Democrats like Senate Majority Leader Harry Reid and House Minority Leader Nancy Pelosi, and Republicans including House Speaker John Boehner and Arizona Sen. John McCain. But he has yet to convince the American public to support him, according to the latest polls, and Congress remains undecided–including many in his own party. The administration has admitted that American citizens who feel they were tricked after faulty evidence led to the 2003 invasion of Iraq may be war-weary. Former President George Bush used the speculation of weapons of mass destruction to justify bringing American troops into Iraq following the Sept. 11, 2001 terrorist attacks.

Progressive groups are inclined to respect and trust Obama, Galland said, but there are “a number of members saying we haven’t seen the evidence. Given our recent history, the public deserves to see the evidence before Congress makes a decision on this.”

The ad airs despite the Obama administration’s aggressive multi-pronged push to convince the public and Congress–as well as the international community–that a limited strike on Syria is the right move. Top members of Obama’s cabinet as well as the president have made several public pleas and appearances.

The president did not gain new global supporters last week after he spent several days abroad making a case against Syria to the world’s top leaders at the G-20 Summit in St. Petersburg, Russia. Then on Saturday he used his weekly address as another attempt to convince more top officials to support his proposal.

“What we’re talking about is not an open-ended intervention. This would not be another Iraq or Afghanistan,” he said. “There would be no American boots on the ground. 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 joined Vice President Joe Biden at his dinner gathering with key Republican moderates at the U.S. Naval Observatory Sunday night as the administration pressed its case and the vice president was expected to host further congressional briefings Monday. The president also canceled a trip to Los Angeles scheduled for early this week. Instead, he will meet with Senate Democrats on Capitol Hill Tuesday and address the country in a televised speech that night at 9 p.m. EST.

Denis McDonough, the White House chief of staff, appeared on each Sunday morning talk show to try to convince a skeptical Congress to approve the president’s proposal.

“Victory means that he is degraded from doing it again and deterred from doing it again,” McDonough said on Meet the Press about Assad’s supposed use of chemical weapons.

U.S. Sec. of State John Kerry during the weekend also continued the push by traveling to Europe.

“This is not some far-off place where something happened that’s just one Arab sect killing another Arab sect on some internal fight. These are chemical weapons, which for almost 100 years the world has banned from usage, and in a time of war, the only people who have used them are Adolf Hitler and Saddam Hussein,” Kerry told reporters Saturday in Paris, France.

National Security Adviser Susan Rice on Monday warned against the potential of other hot spots “flailing up” if the United States isn’t prepared to punish Assad, thus allowing him to proceed, unchecked.

Not pressuring Assad “puts Americans at risk of chemical attacks targeting at our soldiers and diplomats in the region, and even potentially our citizens at home,” she said in her address to theNew American Foundation in Washington on Monday afternoon.

Failing to act increases the likelihood of chemical weapons falling into the hands of terrorists, and threatening Israel, the United States’ closest ally in the region, she said.

There were reports ahead of Rice’s speech that Syria welcomed Russia’s proposal for Damascus to put its chemical weapons under international control to avoid missile strikes, Keir Simmons, NBC News Moscow correspondent, said Monday on Andrea Mitchell Reports. But, he added, it could be a tactic to delay time.

A closed-door bipartisan congressional briefing was also set for Monday that would include top members of the Obama administration’s team including Kerry, Rice, Secretary of Defense Chuck Hagel, Gen. Martin Dempsey, and Director of National Intelligence James Clappper.

More than 52 congressional members remain undecided, according to a Washington Post tally. It could take until next week before the full Senate decides on the drafted proposal because the House has yet to form a completed resolution.

“These strikes are not inevitable,” Galland said. “Congress has a chance to vote ‘no.’”