Originally Published: 15 MAR 23 14:06 ET

By Priscilla Alvarez, CNN

(CNN) -- US Border Patrol Chief Raul Ortiz on Wednesday said the US does not have "operational control" of the southern border, contradicting a stance previously taken by Department of Homeland Security Secretary Alejandro Mayorkas.

Mayorkas has previously maintained in testimony before lawmakers that the department has operational control of the border, though he's been more ambiguous in interviews, citing the statutory definition and saying he's trying to "achieve it." Mayorkas has often served as the focus of Republicans' criticism of the Biden administration's handling of border security.

"Does DHS have operational control of our entire border?" House Homeland Security Committee Chairman Mark Green, a Republican from Tennessee, asked Ortiz on Wednesday as part of a hearing on the situation along the US-Mexico border.

"No, sir," Ortiz responded.

Green followed up with a clip from Mayorkas maintaining that his department has control.

"Do you think Secretary Mayorkas is lying there?" Green asked.

Ortiz declined to say whether Mayorkas was lying, saying: "About 10 years ago we used operational control as a measuring stick of our effectiveness along the southwest border. My new strategy is geared toward mission advantage."

The exchange was part of Wednesday's hearing on what Republicans described from the outset as Mayorkas' "border crisis." The hearing took place in south Texas.

In his opening remarks, Ortiz underscored the challenges facing his agents amid an influx of migrants at the US-Mexico border, telling lawmakers that in some areas, his agency faces "a crisis situation."

"The migration flow represents challenges, and in some areas, a crisis situation," Ortiz said.

The chief also recalled the September 2021 surge of Haitians in Del Rio, Texas, calling it "chaotic."

"We had over 20,000 people show up in one place in a short period of time," he said, adding that agents provided food and aid, and noting that he remains proud of horse patrol, which came under scrutiny.

"I accepted and continue to accept full responsibility for the actions taken," he added.

In January, the administration rolled out a new process that allows migrants from Cuba, Nicaragua and Haiti to apply to come to the US. That process had previously been for Venezuelans. Those who don't apply can be turned back under the Covid-era border restriction, known as Title 42.

Since the process was implemented, encounters along the US-Mexico borders have dropped to the lowest monthly amount since February 2021 and remained lower last month.

Democrats on the House Homeland Security committee did not attend the panel's Wednesday field hearing in Texas. "Unfortunately, it has become clear that Republicans planned to politicize this event from the start, breaking with the Committee's proud history of bipartisanship," ranking member Bennie Thompson said in a statement to CNN Tuesday. White House spokesperson Ian Sams also accused Republicans of "playing partisan games at the border" and suggested that they should "honestly explain to (Ortiz) why they want to slash the funding needed to combat fentanyl trafficking, stop unlawful border crossings, and conduct other important law enforcement efforts at the border."

Republicans have seized on Mayorkas' previous comments in testimony that the department maintains operational control of the border, though the secretary recently explained the challenges in doing so.

Mayorkas told CNN's Chris Wallace last month that his goal is to "achieve operational control" of the border.

Pressed by Wallace on what it means for the border to be secure and if it means people aren't illegally crossing the border, Mayorkas said: "Of course not. By that measure, the border has never been secure, right?"

Asked again by what measure the border is secure, Mayorkas said: "There is not a common definition of that. If one looks at the statutory definition, the literal interpretation of the statutory language, if one person successfully evades law enforcement at the border, then we have breached the security of the border."