Inaction is not an option in Syria, US President Barack Obama said Saturday in his weekly address, published on the White House website.

The president said that the United States cannot “turn a blind eye” to the images coming out of Syria following a reported chemical weapons attack by the Assad regime in a Damascus suburb on August 21. The US estimates that 1,429 people were killed in that attack.

“The US has presented a powerful case to the world that the Syrian government is responsible for this horrific attack on its own people,” the president said.

“This was not only a direct attack on human dignity, it’s a serious threat to our national security.”

Acknowledging the weariness Americans, and others, have over another Mideast war, the president explained that the military intervention he has proposed “would not be another Iraq or Afghanistan. There would be no American boots on the ground.”

Any action the US would take, Obama said, “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.”

The president is seeking congressional approval for a US strike, having secured authorization from a Senate panel this week to order an operation provided it is limited to 90 days and does not involve US boots on the ground.

“I call on members of Congress to come together and stand up for the kind of world we want to live in,” he said, asserting that the “country will be stronger if we act together, and our actions will be more effective.”

The president said that his decision to use military force was “not made lightly.”

But he warned that a failure to respond to this “outrageous” attack in Syria “would increase the risk that chemical weapons would be used again, and could fall into the hands of terrorists and send a horrible signal to other nations that there would be no consequences for their use of these weapons.”

Congress is due to reconvene on Monday.

The coming days represent one of the most intense periods of congressional outreach for a president not known for investing heavily in consultations with Capitol Hill.

Just back from a European trip, Obama is working to salvage a policy whose fate he’s placed in lawmakers’ hands.

His administration’s lobbying campaign culminates Tuesday, the evening before a critical vote is expected in the Senate. Obama will address the nation from the White House to make his case for military action.

“This is not something we’ve fabricated. This is not something that we are using as an excuse for military action,” Obama said on Friday at the close of the G-20 summit. “I was elected to end wars, and not start them.”

Recent surveys show intense American skepticism about military intervention in Syria, even among those who believe Syria’s government used chemical weapons on its people. A Pew Research Center poll completed last week found only 29 percent in favor of a US strike, with 48 percent opposed and 23 percent unsure.

Lawmakers were at the White House on Friday for classified briefings on evidence implicating Assad’s forces in the attack and Obama’s proposal for a military response.

Obama’s chief of staff, Denis McDonough, was preparing to appear on the five major Sunday political talk shows.

McDonough, Secretary of State John Kerry, Vice President Joe Biden and Obama himself were placing calls to lawmakers to urge them to vote yes. On Sunday night, Biden was to host a dinner for a group of Senate Republicans.

Another bipartisan, classified briefing for Congress was scheduled for Monday, and McDonough planned to meet privately Tuesday with the House Democratic Caucus, whose support could be crucial as Obama faces opposition from House Republicans.

House Speaker John Boehner, R-Ohio, and the Democratic leaders in both the House and Senate have backed Obama’s call for a Syria strike, but it’s unclear how many in either party will join them.

The Senate vote expected Wednesday would come a week after the authorization measure cleared the Foreign Relations Committee on a 10-7 vote. The timetable for Obama’s request is less certain in the House, where the measure could face an even rockier time.