House Republicans on Wednesday kicked off formal impeachment hearings against Alejandro N. Mayorkas, the homeland security secretary, accusing him of willfully failing to enforce immigration laws even as leading constitutional experts said there was no basis to do so.
The G.O.P. drive to impeach Mr. Mayorkas is the latest escalation in the party’s effort to attack the Biden administration on immigration, a politically potent issue that has long animated the hard-right Republican base and has become a liability for President Biden in recent months as migration has surged across the U.S.-Mexico border.
But Republicans have struggled to make the case that their policy complaints are enough to support charges of high crimes and misdemeanors.
On Wednesday, G.O.P. lawmakers accused Mr. Mayorkas of fomenting, or at least exacerbating, a surge in migration and drug trafficking across the southern border by failing to execute the full power of the laws that might mitigate the situation.
“After nearly three years of watching this unfold, what other conclusion is there but that this is an intentional crisis?” Representative Mark E. Green, Republican of Tennessee and the chairman of the Homeland Security Committee, said on Wednesday. He argued that Mr. Mayorkas had implemented “open-border policies” knowing that they would be exploited by dangerous cartels.
Democrats maintained that Republicans were unfairly targeting Mr. Mayorkas for simply carrying out Mr. Biden’s policies, in an attempt to satisfy G.O.P. hard-liners who are clamoring for a border crackdown and have threatened a government shutdown to get their way.
“You cannot impeach a cabinet secretary because you don’t like a president’s policies,” said Representative Bennie Thompson of Mississippi, the top Democrat on the committee. “That’s not what impeachment’s for. That’s not what the Constitution says.”
Democrats invited a constitutional expert to back up that argument.
Impeachment “is not supposed to be a routine tool to solve public policy debates,” Frank O. Bowman III, a law professor at the University of Missouri and a nationally recognized impeachment expert, told the House Homeland Security panel. “Based on all the information available to me, I have not found any evidence he has committed high crimes and misdemeanors.”
His sentiment echoed that of a leading constitutional expert routinely cited by Republicans who was the party’s marquee legal witness against the impeachment of former President Donald J. Trump.
“Being bad at your job is not an impeachable offense. Even really bad. Even Mayorkas’s level of bad,” Jonathan Turley, a law professor at George Washington University, wrote in an opinion essay published on Tuesday, which was frequently cited by Democrats during Wednesday’s hearing.
“If that were the case,” Mr. Turley added, “he would be only the latest in a long line of cabinet officers frog-marched into Congress for constitutional termination.”
House Republicans’ case against Mr. Mayorkas has not changed since they signaled their intention to impeach him a year ago. It hinges on the Biden administration’s decision not to end policies that allow for migrants who enter the country illegally to receive parole to remain in the United States while their cases for permanent admission are pending before the immigration courts.
To make their case, they summoned a trio of state attorneys general — all of whom are suing Mr. Mayorkas over the Biden administration’s border policies — to bolster their assertion that unlawful border crossings and fentanyl deaths had become so bad that the only logical conclusion was that Mr. Mayorkas was intentionally trying to endanger the country.
“This body is completely within its constitutional and legal right to bring impeachment proceedings,” Austin Knudsen, the attorney general of Montana, testified.
Republicans also accuse Mr. Mayorkas of lying to Congress about whether the administration had “operational control” of the border, despite Mr. Mayorkas’s testimony that Border Patrol officers and Congress recognize different definitions of the term.
“It clearly was not the intention of the founders to limit the power of congressional impeachment over the executive branch, to limit that to violation of written statute,” said Representative Clay Higgins, Republican of Louisiana.
Democrats noted that Republicans had failed to present any specific evidence against Mr. Mayorkas and accused them of rebranding their political attacks on Mr. Biden’s immigration policy as an impeachment effort.
“It’s the same hearing we’ve had 10, 12 times,” said Representative Dan Goldman, Democrat of New York, who led the prosecution during Mr. Trump’s first impeachment. “Same pig, different lipstick, because we’re now going to call it an impeachment hearing.”