Numerous Democratic lawmakers and immigration advocates used the Father’s Day holiday on Sunday to amplify calls for an end to the Trump administration’s policy of separating migrant families who cross the U.S.–Mexico border illegally.

A wave of Democrats took to Twitter to declare Sunday a "#FathersDayofAction." The representatives sought to raise awareness of the Trump administration's so-called zero tolerance policy and to pressure President Trump Donald John TrumpBiden on Trump's refusal to commit to peaceful transfer of power: 'What country are we in?' Romney: 'Unthinkable and unacceptable' to not commit to peaceful transition of power Two Louisville police officers shot amid Breonna Taylor grand jury protests MORE and Republican leaders to end the practice.

"This #FathersDay, the Trump Administration is CHOOSING to forcibly separate children from their parents who are legally seeking asylum. I repeat, there is NO LAW requiring this," Sen. Bob Menendez Robert (Bob) MenendezKasie Hunt to host lead-in show for MSNBC's 'Morning Joe' Senators ask for removal of tariffs on EU food, wine, spirits: report VOA visa decision could hobble Venezuela coverage MORE (D-N.J.) tweeted.

This #FathersDay, the Trump Administration is CHOOSING to forcibly separate children from their parents who are legally seeking asylum. I repeat, there is NO LAW requiring this. #FathersDayofAction #FamilesBelongTogether pic.twitter.com/WVIIhJNXVO — Senator Bob Menendez (@SenatorMenendez) June 17, 2018

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"This Father's Day, I can't stop thinking about the children being separated from their parents by the Trump administration," Sen. Chris Murphy Christopher (Chris) Scott MurphyDemocratic senator calls for 'more flexible' medical supply chain to counter pandemics The Hill's 12:30 Report - Presented by Facebook - Don't expect a government check anytime soon GOP chairman to release interim report on Biden probe 'in about a week' MORE (D-Conn.) tweeted. "It's time for Congress to pass the #KeepFamiliesTogether Act to put a stop to this inhumane policy."

This Father's Day, I can't stop thinking about the children being separated from their parents by the Trump administration.



It's time for Congress to pass the #KeepFamiliesTogether Act to put a stop to this inhumane policy.



Add your name if you agree: https://t.co/qvSKayrjHh — Chris Murphy (@ChrisMurphyCT) June 17, 2018

"As @realDonaldTrump celebrates #FathersDay, I urge him to rethink the hardline immigration rhetoric put forth by his Administration that creates an environment of unjust racial bias, distrust, profiling & the separation of families," Rep. Adriano Espaillat Adriano de Jesus Espaillat CabralLawmakers call for small business aid at all levels of government The Hill's Morning Report - Sponsored by Facebook - Washington on edge amid SCOTUS vacancy On the Money: Administration to ban TikTok, WeChat | House moves toward bill to avoid government shutdown | Coronavirus relief bills boosted GDP, CBO says MORE (D-N.Y.) tweeted.

As @realDonaldTrump celebrates #FathersDay, I urge him to rethink the hardline immigration rhetoric put forth by his Administration that creates an environment of unjust racial bias, distrust, profiling & the separation of families. #FamiliesBelongTogether #FathersDayOfAction — Adriano Espaillat (@RepEspaillat) June 17, 2018

Some lawmakers took the fight to House Speaker Paul Ryan Paul Davis RyanKenosha will be a good bellwether in 2020 At indoor rally, Pence says election runs through Wisconsin Juan Williams: Breaking down the debates MORE (R-Wis.) by responding to his tweet commemorating Father's Day.

"Happy early #FathersDay to those who didn't have our kids ripped away from us by the new @realDonaldTrump family separation policy that is being enabled by @SpeakerRyan," Rep. Ted Lieu (D-Calif.) tweeted.

Happy early #FathersDay to those who didn't have our kids ripped away from us by the new @realDonaldTrump family separation policy that is being enabled by @SpeakerRyan. https://t.co/g52tqMrDmI — Ted Lieu (@tedlieu) June 17, 2018

Ryan is among the group of Republican lawmakers who have said they oppose the policy that separates children from their parents at the border.

While Trump and White House officials have blamed Democrats for the policy, the practice was enacted earlier this year when Attorney General Jeff Sessions Jefferson (Jeff) Beauregard SessionsGOP set to release controversial Biden report Trump's policies on refugees are as simple as ABCs Ocasio-Cortez, Velázquez call for convention to decide Puerto Rico status MORE announced the Department of Justice would criminally prosecute all adults attempting to cross the U.S.–Mexico border illegally.

Sessions acknowledged the process could lead to children being separated from their parents upon being apprehended.

Trump administration officials have repeatedly defended the policy, arguing that it acts as a deterrent against illegal immigration.

While Democrats and Republicans have spoken out against the practice, the White House has indicated it does not intend to end the policy unilaterally.

As part of an effort to raise awareness and push back against the policy, lawmakers have toured holding facilities where migrants are being kept. A group of House Democrats visited an Immigration and Customs Enforcement facility in New Jersey on Sunday morning.

Sen. Jeff Merkley (D-Ore.) is scheduled to lead a group of congressional lawmakers on a tour of a Brownsville, Texas, facility later on Sunday.

"This #FathersDay, I’m thinking of when my kids were young & how impossibly awful the idea of losing them would have been. Ripping children away from parents is cruel. We need a #FathersDayOfAction to #KeepFamiliesTogether – & that’s why I’m headed back to the TX border right now," Merkley tweeted.

A number of other Democrats and immigration advocates did not mention the president directly, but still used Father's Day to voice opposition to the administration's policy.

New York Gov. Andrew Cuomo (D) asked the acting inspector general of the Department of Homeland Security to look into the treatment of immigrant families.

This #FathersDay the separation of children from their parents at the border weighs heavily on our nation's conscience. I'm calling on the Dept of Homeland Security's Inspector General to investigate the disgraceful and inhumane tactics used by ICE. pic.twitter.com/uxps7r3vt3 — Andrew Cuomo (@NYGovCuomo) June 17, 2018

Chelsea Clinton tweeted that "no parent, no person" should support the separation of families.