Hillary Rodham Clinton said on Tuesday her use of the term "illegal immigrants" was a "poor choice of words" and she pledged not to use it anymore, responding to criticism from immigration activists.

The Democratic presidential candidate was asked about her use of the term to describe people who are in the U.S. illegally during a question-and-answer session on Facebook held by Telemundo. The question came from Jose Antonio Vargas, a filmmaker and journalist whose organization, Define American, has said the terminology is offensive and asked all presidential candidates to stop using it.

"Yes, I will," Clinton wrote during a stop in Boulder, Colorado. "That was a poor choice of words. As I've said throughout this campaign, the people at the heart of this issue are children, parents, families, DREAMers. They have names and hopes and dreams that deserve to be respected."

DREAMers take their name from the acronym for legislation that lays out a process toward citizenship for immigrants who were brought into the country illegally as children and grew up in the United States.

During a town-hall meeting in New Hampshire earlier this month, Clinton said she voted "numerous times when I was a senator to spend money to build a barrier to try to prevent illegal immigrants from coming in. And I do think you have to control your borders."

Clinton has called for expanding President Barack Obama's executive actions on immigration and overhauling U.S. immigration laws, providing a pathway to citizenship for those living in the U.S. illegally.

Her plans mark a sharp contrast with Republican White House hopefuls, who have vowed to roll back the president's immigration orders. Many GOP candidates also routinely use the term "illegals" to refer to immigrants in the country illegally.

Clinton, during a subsequent rally in Boulder, said the U.S. was "fighting for human rights and dignity and freedom" against terrorism and said the U.S. was justified in allowing refugees to enter the U.S. after a "strong vetting process." Republican presidential candidates have largely opposed allowing refugees from Syria into the country. GOP front-runner Donald Trump has suggested he would support ways to track Muslims in the U.S.

"I've heard all of this loose and inflammatory talk about refugees," Clinton said. "And I don't think that does us any good at all in waging and winning the fight against criminals and killers who misuse religion and promote a different set of values than the ones that we believe in."

Clinton met in Boulder early Tuesday with survivors of mass shooting victims, and she later vowed to fight gun violence with tougher gun control laws.

Clinton met with Jane Dougherty, sister of Mary Sherlach, who was slain at the Sandy Hook Elementary School shooting in 2012; Tom Sullivan and Matthew Jenks, the father and brother-in-law, respectively, of Alex Sullivan, who was killed in the 2012 Aurora theater shootings; and Coni Sanders, daughter of Dave Sanders, killed in the 1999 Columbine High School shootings.

"If 33,000 people were dying every year from something else, we'd surely do something about it," Clinton said of U.S. shooting deaths at a Denver rally.

Also Tuesday, the former secretary of state won the endorsement of the Laborers' International Union of North America, which represents about 500,000 construction workers. Clinton has won the support of several large unions representing about 11 million members in total.