(CNN) President Donald Trump's executive order to keep undocumented immigrant parents and children together is "unconstitutional" and did not solve the family separation issue, Rep. David Cicilline said Friday.

"The President's executive order says, 'OK, you don't want kids being separated from their mothers? OK, we'll solve that, we'll say that families can be detained together indefinitely,' " the Rhode Island Democrat said in an interview with CNN's Wolf Blitzer on "The Situation Room."

Cicilline said the executive order would violate the Reno v. Flores ruling barring the government from holding undocumented children for more than 20 days.

"The court in Flores already decided children cannot be held indefinitely, our Constitution prohibits it," Cicilline said. "So the President makes an executive order which is unconstitutional and in the order he says, 'Go to court and try to get them to change the Flores decision.' So this executive order is not well written, not well thought out."

The executive order therefore does not actually end family separations and Trump must go further and end the separations permanently, Cicilline said.

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