As many as 57 percent of this age group see Trump's presidency as illegitimate for a wide range of reasons. Some believe that the whole election process was unfair; others bring up his nationalist rhetoric and policies.
One respondent recalled Trump's campaign speeches in which he vowed he would make Mexico pay for the wall on the border with the US and referred to some Mexican immigrants as criminals and rapists.
"You can't be saying that [if] you're the president," said 21-year-old Florida student Jermaine Anderson.
"I'm thinking, he's saying that most of the people in the world who are raping and killing people are the immigrants. That's not true."
Overall, just 22 percent of young adults approve of Trump, while 62 percent disapprove. One of the poll participants who voted for Trump said he won mostly because his rival Hillary Clinton was even worse choice.
"Obviously America wanted him more than Hillary Clinton," said 30-year-old Rebecca Gallardo, a nursing student from Missouri.
According to another poll by Gallup, based on around 1,500 phone interviews with American adults, the president's approval rating has dropped to a record low 37 percent. Never has any US leader dipped to this point by March of their first term.
Trump has surpassed former President Barack Obama, whom Trump once mocked for having a "record low" Gallup approval rating of 39 percent in August 2011.
Trump entered office on 20 January with an approval rating of around 45 percent.
