Democratic candidates are responding to the GOP's strong stance on immigration, especially after frontrunner Donald Trump's controversial comments at the recent Republican debate.

Sen. Bernie Sanders said, "The idea in the year 2015 of attacking people in sometimes ugly terminology because they come from another country is unacceptable to me."

"What is being said by those running on the Republican side is incredibly offensive and it is unrealistic, it is mean spirited. I've run out of adjectives," said Hillary Clinton. "The idea that the United States of America would round up 11 or 12 million people and deport them is absolute fantasy."