Former Texas representative Beto O'Rourke, who is running for the Democratic presidential nomination, on Thursday compared President Donald Trump to the Third Reich, referring to the regime of Nazi dictator Adolf Hitler who presided over the Holocaust.

O'Rourke spoke at a campaign event in Carroll, Iowa, earlier in the morning, where he reflected on the times he went to elementary schools around Valentine's Day and delivered cards from the students to veterans.

"Every year that I was in Congress we would go to a different elementary school around Valentine's day and pick up Valentine's Day cards for veterans that were hand-drawn by second grade or third grade classrooms, and then we would take them over to the VA and we would want to make sure that those veterans understood the generation coming up cares for them and is grateful for what they have done for this country," O'Rourke said.

He then reflected on a third grade Mexican-American girl asking him why Trump didn't like her.

"What is that doing to her head and to her perception of herself and what she's able to contribute this country, when the president of the United States has called Mexican immigrants rapists and criminals?" O'Rourke said. "He then went on to call asylum seekers animals and an infestation. Now we would not be surprised if in the Third Reich other human beings were described as an infestation, as a cockroach or a pest that you would want to kill."

This isn't the first time that Trump's administration has been compared to the Nazi regime, which resulted in the death of approximately 6 million Jews.

CNN analyst and former Obama official Samantha Vinograd said last month after Trump's CPAC speech that "On a personal level, ‘preserving our heritage, reclaiming our heritage' sounds a lot like a certain leader that killed members of my family and about 6 million other Jews in the 1940s."

Rep. Hank Johnson (D., Ga.) made a similar comparison back in January at an NAACP event to mark the anniversary of the 1863 Emancipation Proclamation.

"Much like how Hitler took over the Nazi party, Trump has taken over the Republican Party," Johnson said.