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Immigration and Customs Enforcement began its promised raids on undocumented immigrants on Saturday—but they didn’t get off to a good start.

Federal immigration agents tried and failed to raid two New York City homes on Saturday. Officials were turned away by people at those residences because the agents reportedly did not have warrants.

A spokesperson for ICE declined to give any specific details about the failed raids to reporters, commenting to the Wall Street Journal: “As always, ICE prioritizes the arrest and removal of unlawfully present aliens who pose a threat to national security, public safety and border security.”

The raids are set to begin in earnest on Sunday in 10 cities: Miami, Atlanta, Chicago, Baltimore, Denver, Houston, Los Angeles, New Orleans, New York, and San Francisco. Most of these municipalities are heavily Democratic, and some have declared themselves to be sanctuary cities, resisting cooperation with federal immigration enforcement.

Immigration activists in these cities have promised to mobilize against the raids. Democratic presidential hopefuls have also spoken out publicly against the raids, signaling that immigration will once again figure prominently in the run-up to the 2020 presidential election.

President Trump’s ICE raids are inhumane. His scare tactics solve nothing. We shouldn't be terrorizing communities and splitting up families. We should provide a pathway to citizenship and find a lasting solution. — Joe Biden (@JoeBiden) July 13, 2019

As ICE raids begin, know your rights. Follow these guidelines from the @ACLU and stay safe. https://t.co/cc4lp5RVw1 — Kamala Harris (@KamalaHarris) July 14, 2019

Donald Trump may be willing to look the other way while criminal abuses toward immigrants pile up, but make no mistake: President Elizabeth Warren will not. #NN19 pic.twitter.com/buNRwkot46 — Elizabeth Warren (@ewarren) July 13, 2019

President Donald Trump scrapped a previous series of planned raids earlier this year. Still, the president has remained steadfast in his promise of “removing the millions of illegal aliens who have illicitly found their way into the United States.”

Next week ICE will begin the process of removing the millions of illegal aliens who have illicitly found their way into the United States. They will be removed as fast as they come in. Mexico, using their strong immigration laws, is doing a very good job of stopping people……. — Donald J. Trump (@realDonaldTrump) June 18, 2019

That is pretty much impossible, given that ICE doesn’t have anywhere near the resources needed to make good on Trump’s repeated threats.

Trump’s critics have seized on the moment to denounce the raids. Speaking to the Journal, Vanita Gupta, CEO of the Leadership Council on Civil and Human Rights Council and a former Obama Justice Department official, called them a “craven action [that] may motivate his political base.”

Meanwhile, back in New York City, ICE agents promised to return to the two residences at which they’d been turned away. This time, they’ll have warrants.