Thousands of undocumented immigrants were waiting in fear and uncertainty ahead of nationwide raids Sunday that President Donald Trump said would lead to a wave of expulsions.

Demonstrators in dozens of cities protested the planned raids, and local and state officials called for restraint, but to no effect.

Before dawn on Sunday, agents from Immigration and Customs Enforcement (ICE) are expected to hit the streets of at least 10 major American cities with plans to arrest some 2,000 undocumented migrants who entered the United States recently.

Protesters hold signs during a rally in Daley Plaza.

The scope of the operation appears far more modest than the "millions" Trump had promised would be detained and expelled when he first mentioned the raids -- and subsequently postponed -- last month.

But that has not eased the anguish felt by those who fear they might be targeted.

'It's traumatizing'

"This uncertainty, this fear, is wreaking havoc," Chicago Mayor Lori Lightfoot said on CNN. "It's traumatizing people."

Mary Grace Bertulfo stands inside her cage made out of cardboard during a rally in Daley Plaza.

Trump insisted on Friday that "most mayors" want the raids.

"Most mayors do. You know why? They don't want to have crimes in their cities," he said, repeating his frequent -- and incorrect -- assertion that migrants are more likely to be criminals than native-born Americans.

Several mayors have expressed concern about the federal operation.

Protesters attend rally calling for an end to criminalization, detention and deportations of migrants.

Millions 'in line'

"We have millions of people standing in line waiting to become citizens of this country," Trump said Friday.

The United States has been struggling for more than a year with a migration crisis on its southern border, as thousands of people stream into the US each month, mostly from Central American countries riven by violence and poverty.

Alisa Davies, dressed as the statue of liberty holds dolls to protest the treatment of immigrants in detention centers.

The number of undocumented arrivals totaled more than 100,000 last month -- down 28 percent from May but still at a "critical" level, according to the Department of Homeland Security.

On Friday and Saturday, dozens of protests were organized across the country by groups demanding the closing of overcrowded detention centers and opposing the planned raids.

Agence France-Presse