Rep. Ted Lieu (D-Calif.) late Monday joined a growing list of Democrats in calling for Department of Homeland Security Secretary Kirstjen Nielsen Kirstjen Michele NielsenMore than million in DHS contracts awarded to firm of acting secretary's wife: report DHS IG won't investigate after watchdog said Wolf, Cuccinelli appointments violated law Appeals court sides with Trump over drawdown of immigrant protections MORE to resign over her defense of the separation of migrant families.

"This lie is the last straw. I join @KamalaHarris in calling on Secretary Nielsen to resign. It's not just that @SecNielsen has a policy of ripping children away from parents, it's her volume of lies about the new policy," Lieu tweeted.

"Her credibility has been shredded. Nielsen needs to go," he added.

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This lie is the last straw. I join @KamalaHarris in calling on Secretary Nielsen to resign. It's not just that @SecNielsen has a policy of ripping children away from parents, it's her volume of lies about the new policy.



Her credibility has been shredded. Nielsen needs to go. https://t.co/U4C3Jgz7rD — Ted Lieu (@tedlieu) June 18, 2018

Lieu's comments came after Nielsen fielded questions on the Trump administration's "zero tolerance" policy, which has led to the separation of thousands of migrant children from their parents.

She defended the policy and declared "Congress alone can fix it," even the practice resulted from an order from Attorney General Jeff Sessions.

Lieu joined Democratic Sens. Kamala Harris Kamala HarrisHarris faces pivotal moment with Supreme Court battle Nearly 40 Democratic senators call for climate change questions in debates Joe Biden has long forgotten North Carolina: Today's visit is too late MORE (Calif.) and Mazie Hirono Mazie Keiko HironoManchin defends Supreme Court candidate Barrett: 'It's awful to bring in religion' Democrats shoot down talk of expanding Supreme Court Democrats unveil plan declaring racism a public health issue MORE (Hawaii) and House Minority Leader Nancy Pelosi Nancy PelosiHoyer: House should vote on COVID-19 aid — with or without a bipartisan deal Ruth Bader Ginsburg lies in repose at Supreme Court McCarthy threatens motion to oust Pelosi if she moves forward with impeachment MORE (D-Calif.) in calling on Nielsen to resign.

Democrats and Republicans alike have demanded that the Trump administration end the practice, which has separated migrant families at the border. Multiple lawmakers have crafted legislation to end it, though it's unclear if both parties can come to a consensus on a bill.