(CNN) President Donald Trump plans to "revisit" his administration's decision on the Deferred Action for Childhood Arrivals program if Congress is unable to pass legislation on the issue within six months, he announced in a tweet Tuesday night.

"Congress now has 6 months to legalize DACA (something the Obama Administration was unable to do). If they can't, I will revisit this issue!" Trump wrote.

Congress now has 6 months to legalize DACA (something the Obama Administration was unable to do). If they can't, I will revisit this issue! — Donald J. Trump (@realDonaldTrump) September 6, 2017

The Trump administration several times Tuesday referred to President Barack Obama's use of executive authority to pass DACA as vulnerable to legal challenges.

"The Department of Justice cannot defend this overreach," Sessions said at the Justice Department. "There is nothing compassionate about the failure to enforce immigration laws. Enforcing the law saves lives, protects communities and taxpayers, and prevents human suffering. Failure to enforce the laws in the past has put our nation at risk of crime, violence and even terrorism. The compassionate thing is to end the lawlessness, (and) enforce our laws."

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