The Democrats’ response to Kirstjen Nielsen’s resignation on Sunday as secretary of Homeland Security was biting.

They questioned her leadership. They slammed her “cruel” enforcement of President Donald Trump’s immigration policies. They welcomed her departure.

They also recognized that Nielsen’s resignation won’t change Trump’s efforts to address his declaration of a national emergency at the country’s southern border.

“It is deeply alarming that the Trump Administration official who put children in cages is reportedly resigning because she is not extreme enough for the White House’s liking,” House Speaker Nancy Pelosi said in a statement. “The President’s dangerous and cruel anti-immigrant policies have only worsened the humanitarian suffering at the border and inflicted vast suffering on the families who have been torn apart.”

Senate Minority Leader Chuck Schumer echoed Pelosi: “When even the most radical voices in the administration aren’t radical enough for President Trump, you know he’s completely lost touch with the American people,” the New York senator said in a statement.

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Four 2020 Democratic presidential candidates sounded off via Twitter, using Nielsen’s resignation as another opportunity to criticize her 2018 defense of the Trump administration’s zero-tolerance immigration policy that led to the separation of more than 2,500 children from their parents who illegally crossed the border.

“About time,” Massachusetts Sen. Elizabeth Warren said, adding that Nielsen’s “legacy of tearing innocent families apart will follow her for the rest of her life—and she should be ashamed of the role she played.”

“Kirstjen Nielsen misled the American people and defended Trump’s inhumane policy of separating children from their parents,” California Sen. Kamala Harris said. "It was long past time for her to go."

Former Housing and Urban Development Secretary Julian Castro called Nielsen “a willing partner in the most cruel and short-sighted immigration agenda in decades,” and New York Sen. Kirsten Gillibrand blasted Nielsen’s support for “the administration’s inhumane treatment of immigrant families” and called for “a moral reset on immigration policies.”

But, Gillibrand lamented, “We won’t get that in this administration.”

While calling Nielsen’s 16-month stint as DHS secretary a “disaster from the start,” Rep. Bennie Thompson, D-Mississippi, also stressed that she can’t “serve as a scapegoat.”

In a statement, Thompson, chairman of the House Homeland Security Committee, said: “Let me be clear, President Trump is to blame for making the situation at the border worse. His terrible and cruel policies have broken families apart and have caused chaos in our immigration system. This is now self-evident.”

Nielsen’s departure comes as a surge of migrants has overwhelmed the U.S. immigration in recent months, leading Trump to threaten closure of the country’s border with Mexico and cut off aid to Central American countries that migrants continue to flee.

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Border Patrol agents apprehended 66,450 people illegally crossing the southern border in February, according to CBP data, including a record high of 36,174 members of families and 6,825 unaccompanied minors.

Just last week, Nielsen likened the situation at the border to a “massive (Category) 5 hurricane disaster” during a Fox News interview.

Her efforts to support the Trump administration drew praise from a few Republican lawmakers on Sunday night.

In a statement, Senate Majority Leader Mitch McConnell praised Nielsen's service "to the administration and to the American people."

“From natural disasters to cybersecurity threats, the Department of Homeland Security protects Americans on countless fronts — including, of course, the front lines of the security and humanitarian crisis on our southern border," the Kentucky senator said.

“Secretary Nielsen served her country honorably as Homeland Security Secretary, despite facing numerous challenges including dire conditions at our southwest border,” Alabama Rep. Mike Rogers, ranking member of the House Homeland Security Committee, said in a statement.

Oklahoma Sen. James Lankford, via Twitter, thanked Nielsen “for her tireless work to honor legal immigration and stop people from using children as pawns for illegal immigration.”