On Wednesday, more than 11 million undocumented immigrants woke up to the news that Donald Trump, the candidate who promised to deport millions of "criminal aliens" starting his first day in office, had been elected president of the United States. Facing a suddenly uncertain future, many reacted with alarm and fear.

In the days since Trump's victory, mayors from major cities across the county, including New York, Chicago and San Francisco, have eased concerns by vowing not to coordinate with federal law enforcement to deport undocumented residents. The flood of announcements sets the stage for a major battle with Trump, who has said he will cut all federal funding to the so-called sanctuary cities immediately following his Jan. 20 inauguration.

On Monday, Chicago Mayor Rahm Emanuel became the latest big-city leader to follow the trend, announcing at a news conference that Chicago would continue to bar government workers and police officers from asking residents about their immigration status. According to the Chicago Tribune, the bar has been in place since 1985.

"To all those who are, after Tuesday's election, very nervous and filled with anxiety as we've spoken to, you are safe in Chicago, you are secure in Chicago and you are supported in Chicago," Emanuel said. "Chicago will always be a sanctuary city."

Emanuel's announcement follows a similar pledge Friday from New York City Mayor Bill de Blasio. When asked what he would tell concerned Muslim residents, de Blasio said, "We have your back."

"I want everyone in New York City to know that we are standing by our values and we will fight to protect our values," he said, according to DNAinfo.

Following the mayor's claim that he would commit to working with the Trump administration, de Blasio said his team called Trump to schedule a phone conversation to discuss the issue.

In Los Angeles, Police Chief Charlie Beck announced that he plans to preserve the LAPD's independence from federal immigration policies, a rule that dates to 1979, when Los Angeles became the country's first "sanctuary city." Los Angeles County is home to more than 1 million of the roughly 11 million illegal immigrants in the U.S., the Los Angeles Times reported.

Critics of sanctuary cities have drawn on incidents such as the death of Kate Steinle, a 32-year-old woman killed by Mexican immigrant Juan Francisco Lopez-Sanchez on a San Francisco Pier in July 2015.

Steinle's parents sued former San Francisco Sheriff Ross Mirkarimi in May, claiming he should not have released Lopez-Sanchez from jail in April 2015, according to the San Francisco Chronicle. Mirkarimi's office declined to prosecute Lopez-Sanchez on a decades-old marijuana charge, freeing him under the city's sanctuary policy.

On Monday, San Francisco Mayor Ed Lee said San Francisco will remain a sanctuary city despite Trump's threats to cut funding. San Francisco receives about $480 million from the federal government and an additional $900 million from the state, most of which is pass-through federal money, the Chronicle reported.

Other major cities have also announced their intent to oppose Trump's deportation policy, including Minneapolis. Mayor Betsy Hodges said in a statement Saturday that she could continue to "stand by and fight for immigrants" in Minneapolis, claiming that doing otherwise would compromise the city's safety.

"If police officers were to do the work of ICE [U.S. Immigration and Customs Enforcement] it would harm our ability to keep people safe and solve crimes," Hodges's statement read. "Witnesses and victims of crimes won't come forward if they think our police officers will question or detain them about their immigration status."

Federal funding accounted for 3 percent of the city's 2015 budget, according to the Minneapolis newspaper City Pages.

Some mayors have taken a less confident tone when asked how they planned to handle the loss of funding if Trump goes through with his promise. Seattle Mayor Ed Murray, who promised to maintain his city's sanctuary status on Wednesday, admitted he was "very concerned" about receiving funding from the Trump administration, according to the Seattle Times.

During his pledge Thursday to protect undocumented immigrants, Philadelphia Mayor Jim Kenney cited the Fourth Amendment, saying that it protects being "held against your will without a warrant." But he declined to address what would happen if Trump withheld federal funding, per Philly.com.

"We'll cross that bridge when we come to it, and we'll see how it goes and we'll try to figure something out," Kenney said.

Critics have taken to social media to label the establishment of sanctuary cities as "sedition," while others have decried the policy over the loss of family members to violence. Los Angeles man Jamiel Shaw Sr. told CBS LA that his son was killed by a member of the 18th St. Gang who was in the U.S. illegally. Shaw has spoken at a Trump rally and appeared in one of his ads.

Vice President of the National Border Patrol Council Shawn Moran, speaking on Fox & Friends, claimed that sanctuary cities incentivize lawbreaking. He cited the "millions of people that are already in our cities that are committing crimes and killing American citizens, whether it be through domestic violence, drunk driving, things like that."

"Many Americans, thousands of them, have been killed by illegal aliens," Moran said.

Trump made the same claim at an Oct. 27 rally in Springfield, Ohio, though PolitiFact noted there is a lack of data to back up the claim one way or another.

Since his victory on Nov. 8, the president-elect has begun to offer a clearer picture of what his immigration policies might entail. In a "60 Minutes" interview Sunday, Trump said he planned to deport 2 million to 3 million undocumented immigrants with "criminal records," echoing Republican National Committee Chairman Reince Priebus's statement on MSNBC's Morning Joe Wednesday that Trump only plans to deport "people who have committed crimes."

The number of such immigrants living in the U.S. is approximately 820,000, according to FiveThirtyEight, well under the range Trump gave in his interview.

Priebus, who has since been named Trump's chief of staff, left the door open to further policy beyond deporting undocumented immigrants with criminal records.