(USA Today) PHOENIX — The same man who staged a contentious rally outside a Phoenix mosque in May led a noisy protest Sunday in Phoenix to denounce Walmart pulling Confederate flag merchandise from its shelves.

Scores of supporters who gathered in a west Phoenix store parking lot were met by equally noisy opponents.

The self-proclaimed "patriots" group, which organized the event, waved both American and Confederate flags while chanting "U-S-A" alongside their pickup trucks.

The rally in Phoenix comes as South Carolina is expected to begin debate Monday onthe future of the Confederate flag that flies at the Confederate monument on the front lawn of the capitol grounds. The flag has been there since a 2000 legislative compromise moved it from the top of the Statehouse dome.

Taking down the flag in South Carolina requires a two-thirds supermajority in both the House and the Senate. In the Senate, a bill already has been introduced that would move the flag to the Confederate relic room, a museum just down the road from the Statehouse.

In Phoenix on Sunday, customers pushing carts full of groceries did double-takes while returning to their vehicles. Many returned with cellphones ready, hoping to capture the scene.

About an hour later, Walmart management asked protesters to leave the property. Both groups flocked to a bus stop, in front of an O'Reilly Auto Parts store, where numerous pedestrians lined the adjacent parking lot.

Tensions peaked when a young counter-protester stomped an American flag into the dirt, only for it to be wrestled out from underneath him by Jon Ritzheimer, a Phoenix man who promoted the rally to support the Confederate symbol as well as the mosque event in May.

He shouted it was disrespectful to the memory of fallen veterans and moved out of the feuding crowd. Dusting it off in a dry breeze, Ritzheimer flew the nation's flag alongside a Confederate one as cars drove by, occasionally honking horns.

A former Marine, Ritzheimer organized a contentious "freedom of speech" rally outside a Phoenix mosque May 30. Police estimated about 500 people attended the rally in which protesters and counter-protesters verbally sparred for hours.

For Sunday's event, Ritzheimer said he was at the protest in opposition of Walmart refusing to sell Confederate flag merchandise in its stores, but he remained relatively quiet throughout the two-hour event as others shouted and chanted.

The announcement by the world's biggest retailer to drop the Confederate flag merchandise from in-store and online stock came in the wake of the shooting deaths of nine people at a historic Black church in Charleston, S.C.

That shooting prompted widespread calls from leading politicians of both major parties to remove the Confederate flag from public spaces.

The shooting also reignited the debate over the flag's symbolism, including on Phoenix's streets Sunday.

"This flag represents the KKK and promotes a hate agenda against people of color in this country," said counter-protester Amy McMullen. "It's repulsive to people, so why should Walmart sell it?"

One of the most animated Confederate-flag supporters, Nohl Rosen, a self-described "patriot" of Phoenix, remained steadfast in his beliefs after the demonstration.

"The Confederate flag is not a racist flag; it's a part of our history," said Rosen. "You can't erase history. They're trying to erase history and re-create it to an image they want."

Many counter-protesters, donning camouflage and black bandannas over their mouths to obscure their faces, clashed with Rosen and others.

Sunday's heated event drew about 100 people, according to an unofficial police count. Phoenix police spokesman Lt. Randy Force said 11 officers were at the event after Walmart management called police. Some protesters were armed.

Police followed participants to the second location, where many shouted from megaphones and taunted each other by hurling political jabs and insults.

Observers outside of the fray were critical of the demonstration, with many saying they were turned off by the vitriol and banter.

Guadalupe Ismail, who went to Walmart to do grocery shopping, expected a show after noticing demonstrators wearing masks and costumes. She said she moved to Phoenix six months ago from Georgia.

"I didn't know it was a hatred show," she said. "It wouldn't surprise me if this happened in Georgia, but I was shocked to see it in Arizona. It's very sad."