Over 179,000 illegal aliens convicted of crimes are still roaming free in the U.S. and committing new crimes "every day," while at the same time, the number of criminal aliens deported has dropped to nearly half the level seen in 2011, according to lawmakers and the agency tasked with deporting them, Immigration and Customs Enforcement (ICE).

"There are 179,027 undocumented criminals with final orders of removal at large in the United States today, thousands of victims, and many of the agency's own officers who are unable to do the job they signed up to do," Sen. Chuck Grassley, R-Iowa, chairman of the Senate Judiciary Committee, said during a hearing Wednesday, reported The Washington Free Beacon.

Sen. Jeff Sessions, R-Ala., another member of the committee, told ICE Director Sarah Saldana that ICE "removed 150,000 criminal aliens from the interior. In Fiscal Year '12 it dropped to 135,000, in Fiscal Year '13 it dropped to 110,000, in Fiscal Year '14 to 86,000. And in Fiscal Year '15, this year, we believe the number is only around 63,000," reported Breitbart.

Sessions asked Saldana to explain the "alarming development," to which Saldana responded by saying that crackdowns at the border have left fewer people for ICE to deport.

Saldana also claimed that ICE cannot deport criminal aliens without the cooperation of their home country, and there are "a whole bunch" of countries that refuse to take back their citizens. Saldana named Haiti, China and India, and said she couldn't remember the rest but would provide lawmakers with a list, according to CNS News.

In recent years, ICE has released between 30,000 to 40,000 illegal criminal immigrants from custody because of legal restrictions on how long the agency is allowed to detain an individual, Saldana said. Without cooperation from an immigrants' home country, ICE has no choice but to release them back on to American streets.

"Whether it's a result of protracted appeals or refusal of a country to accept its nationals back, this decision accounts for somewhere between 30,000 and 40,000 convicted criminal alien releases in recent years," Saldana said, adding that the number has dropped.

But Sessions wasn't satisfied, saying, "Not only are total removals down, but the number of removals of criminal aliens from the interior of United States, the so-called priority, has decreased significantly," according to the Beacon.

"The reason for this decrease is not because there are fewer criminal aliens in the U.S. today then just a few years ago, there are hundreds of thousands of known criminal aliens in the U.S," he said, noting that it cannot be blamed on a lack of financial resources, as Congress has increased funding.

The Obama administration appears to be "substantially less with substantially more," he said. "There are currently about 900,000 undocumented immigrants present in the United States who have been ordered to leave the country, but have not. And despite receiving $3.4 billion for detention and removal operations in 2015, Homeland Security only managed to remove roughly 63,000 undocumented criminals from the United States."