Washington - Waving signs and placards, at least 200 protesters gathered at the White House on Saturday before marching to Capitol Hill, in a demonstration opposing possible US military strikes against Syria.
The midday rally was one of several planned in cities across the United States Saturday and ahead of larger planned protest in Washington on Monday.
"Congressional offices are being flooded with calls, faxes and e-mails," said Sarah Sloan, of the Answer Coalition - the group organising the protest - in a statement before the demonstration.
"Congressional officials report that by a margin of 100 to one, people are telling the elected representatives from their district that they should vote no on the war resolution," she added.
"Because of the deep split inside the political establishment, what the people do can make a huge difference," she said.
The protests were held with the nation sharply divided over President Barack Obama's efforts to launch military strikes to punish the regime of Syrian President Bashar al-Assad for alleged chemical weapons attacks against his countrymen.
Obama declared in his weekly address on Saturday morning that "we cannot turn a blind eye to images like the ones we've seen out of Syria".
He was briefed later in the day by his Chief of Staff Denis McDonough on the latest consultations with lawmakers about an impending vote on military action there, according to a White House official.
The official said Obama planned to make phone calls to members of Congress over the weekend, to urge them to support the proposed military strikes, which have met stiff opposition in the US public and in Congress.
Congress reconvenes on Monday, and Obama addresses the nation the following day about a possible US response to the August 21 attack that left hundreds dead on the outskirts of Damascus.