Detainees may arrive in Aurora from the U.S.-Mexico border or New York City, far away from family and a known place.
About 70 former U.S. attorneys, including John Walsh of Colorado, call the Trump policy "dangerous, expensive, and inconsistent with the values of the institution in which we served."
A Denver teacher wrote "Todos Vamos A Estar Bien" to help children and others see deportation through a kid's eyes.
"Both of us support a pathway to citizenship for the dreamers, and both of us support border security," said Sen. Michael Bennet, a Democrat.
I refuse to meet with the President under these kinds of threats and fear mongering," Denver Mayor Michael Hancock said.
Colorado's U.S. senators both voted Monday in favor of a temporary spending deal that allowed the federal government to reopen.
Thursday is the deadline for many of Colorado estimated 1,100 undocumented college students to reapply for an important federal program.
DACA currently protects more than 17,000 Colorado minors from deportation.
Mayor Michael Hancock joins dozens of other mayors and jurisdictions in the lawsuit, and is not worried about angering the White House.