Washington — Top Department of Homeland Security officials on Thursday brushed aside Republican criticism of the Biden administration’s immigration agenda, defending decisions to process unaccompanied migrant children at the southern border and curtail immigration arrests in the interior of the country. Republican senators wielding poster boards with apprehension numbers pressed Homeland Security Secretary Alejandro Mayorkas on the Biden administration’s refusal to expel unaccompanied children under a Trump-era public health order known as Title 42 that is still being used to turn back migrant adults and families to Mexico without a court hearing. Senator Mitt Romney, a Republican from Utah, said the policy decision encouraged a record number of Central American children to journey north. “Unaccompanied children are being led into a country. Is this not a massive failure that would suggest that the administration needs to take immediate action to remedy what we’re seeing here?” Romney inquired. “Senator, we have taken immediate action with respect to the unaccompanied children,” Mayorkas responded, citing DHS’ progress in transferring children out of border patrol custody. “There’s a surge, and it is undeniable,” Senator Ron Johnson exclaimed. “And yet you are denying it.” Meanwhile, several Democratic lawmakers expressed concerns that the continued use of Title 42 results in the voluntary separation of families. While most single adults and some families arriving at the southwest border are turned away under Title 42 without being able to apply for asylum, the Biden administration made an exception for unaccompanied children who are transferred into HHS custody, as required by anti-trafficking law. During the hearing before the Senate Homeland Security and Governmental Affairs committee, Mayorkas acknowledged the exception has resulted in the voluntary separation of migrant children from their families, but stopped short of assigning a number to the troubling phenomenon. “We are certainly hearing anecdotally that some families self-separate to allow their children to enter the United States unaccompanied. That speaks to the trauma these families have endured and their desperation to give their children a better life.” Since President Biden took office, Border Patrol agents have encountered more than 2,100 unaccompanied migrant children who are believed to have left their families voluntarily in order to seek asylum in the U.S, according to government data obtained by CBS News. Probed on whether the policy would end amid a rise in COVID-19 vaccinations and loosened CDC health guidelines, Mayorkas replied, “I don’t have a timetable in sight.” Mayorkas observed that the migrant children arriving at the U.S.-Mexico border are fleeing poverty and violence in their home countries, noting that many are of “very tender age.” “We cannot overstate the trauma that some of these children have endured. It speaks to, on the one hand, the cruelty of some, but it also speaks poignantly of the resilience of the human spirit,” Mayorkas said. “It is remarkable what these children have gone through, but how they can see a better day ahead. It is our responsibility, the responsibility of humanity, to address the needs of these children.” During a heated exchange, Missouri Senator Josh Hawley, a Republican, grilled Mayorkas on the recent decision to discontinue flights that had been transporting migrant families across southern border states for the purposes of expelling them under Title 42. Hawley asked Mayorkas if the policy change was enacted at the insistence of “leftwing groups.” Mayorkas replied DHS does not make policy decisions “because of pressure from outside groups.” That is not to say that the department doesn’t accept input from outside entities — he noted that DHS has been discussing the matter with the American Civil Liberties Union, which is challenging the expulsions of migrant families in federal court. The secretary acknowledged to lawmakers that the Biden administration is “studying” gaps and gates in the wall construction initiated under the Trump administration to determine how best to secure the U.S.-Mexico border. “We have committed to finishing the levees, as well as addressing the erosion of land under roads adjacent to the wall as two public health imperatives,” Mayorkas told Oklahoma GOP Senator James Lankford. “What is the most effective way to address gates and the completion of gates, as well as the closing of gaps?That is something that is under review now.” Earlier this month, the Pentagon announced that it would cancel all border wall construction projects paid for with Department of Defense funds redirected from military schools, training facilities and other projects by President Trump. Mayorkas told members of Congress that the Biden administration is considering equipping HHS with a “federal workforce” to address recurring spikes in migration. “Because we all know that surges arise periodically,” the Secretary said. “They arose in 2019. They arose in 2016. They arose in 2014 and well before then.” During a separate hearing before the House Appropriations Committee, Tae Johnson, the interim head of Immigration and Customs Enforcement (ICE), defended Biden administration guidelines instructing deportations agents to prioritize the arrest of immigrants deemed to pose a national security threat, recent border-crossers and those with certain criminal records. Johnson conceded that overall ICE arrests have “gone down a bit” in recent months but said arrests of immigrants who fall within the Biden administration’s enforcement priorities have “gone up.” In March and April, ICE officers made 2,200 arrests of immigrants deemed to fall within these three priority groups, Johnson said. “While the overall apprehensions are down, I think when you have officers focusing on what they believe are the worst of the worst, then they are actually much more able to make a more meaningful impact on public safety,” Johnson told lawmakers. He also testified that the Biden administration’s continued use of the Title 42 public health edict is “critical” to ensuring the agency has “adequate space for social distancing” in its sprawling civil immigration detention system, the largest in the world.. “The loss of Title 42 could create additional pressure on our immigration system,” he warned. Pressed by Democratic Congresswoman Lucille Roybal-Allard, Johnson promised to conduct a “full review” of ICE’s detainee population to make sure the cases of those held by the agency meet the new enforcement priorities. There are currently 15,700 immigrants in ICE detention, according to agency data.