WASHINGTON – The revelation late Thursday that the White House tried multiple times to pressure immigration authorities into releasing migrants on the streets of sanctuary cities did not go over well with Democrats, who denounced the Trump administration as cruel.

The plan, reported by the Washington Post, was concocted to retaliate against Democrats and target sanctuary cities in liberal strongholds. It didn't come to fruition after pushback from U.S. Immigration and Customs Enforcement, the Post reported. ICE rejected the idea after at first thinking it was a joke, the Post reported.

Members of Congress and immigration advocates called the idea inhumane and called for those within President Donald Trump's administration to be held accountable.

"This reporting exposes yet a new level of inhumanity in this Administration," Rep. Marcy Kaptur, D-Ohio, wrote on Twitter. "Those who pursued this disgusting policy are beneath the dignity of the offices they hold and must be held to account."

More:A multimillion-dollar question: What's a 'sanctuary city?'

The White House did not immediately respond to inquires about the proposal. In a statement to the Post, the White House said, "This was just a suggestion that was floated and rejected, which ended any further discussion." The Post reported that the proposal sought to ease the bed shortage at immigration detention centers while also retaliating against sanctuary cities and "send a message to Democrats."

House Speaker Nancy Pelosi's district was specifically targeted, according to the Post, noting that the White House wanted to transport migrants into her congressional district in San Francisco.

Ashley Etienne, a spokeswoman for Pelosi, called the proposal "despicable."

"The extent of this Administration’s cynicism and cruelty cannot be overstated," Etienne said in a statement. "Using human beings — including little children — as pawns in their warped game to perpetuate fear and demonize immigrants is despicable, and in some cases, criminal."

Rep. Mike Quigley, D-Ill., agreed.

"Immigrants are people. Not pawns to deploy in the President's petty political fights," Quigley said on Twitter. "@realDonaldTrump’s cruelty knows no limits."

Former Secretary of Housing and Urban Development Julián Castro, who is running for president in 2020, reacted to the news live on CNN during a town hall.

"The cruelty of this administration never seems to end," Castro said, noting the list of Trump's immigration policies that have been criticized or challenged in court. "These folks want us to choose cruelty as a weapon against these people and against political opponents."

Actress and activist Alyssa Milano called the proposal "so sick and twisted." Other activists chimed in, also denouncing the idea.

"Trump is failing and flailing at the border, so he’s looking to blame Democrats with a desperate and cynical ploy. Despicable," said Frank Sharry, president of America’s Voice, a progressive group that advocates for immigration-system reform. "This is what you’d expect from an out-of-control 12-year-old bully, not a president of the United States."

Contributing: Daniel Gonzalez, The Arizona Republic.