Correction: An earlier version of this story reported that Alejandro Mayorkas had testified he met Terry McAuliffe one year ago. It was actually about two years ago. The story has been corrected.

The Obama administration’s nominee to be deputy homeland security chief on Thursday strongly denied giving improper help to a politically connected technology firm, calling the allegations “unequivocally false.”

Alejandro Mayorkas, a top immigration official, is under scrutiny by the Department of Homeland Security’s inspector general for allegations that he improperly intervened to assist an electric-car company seeking U.S. visas for Chinese investors, according to congressional aides and documents.

“I have never in my career used undue influence to influence the outcome of a case,” Mayorkas testified Thursday in front of the Senate Homeland Security and Governmental Affairs Committee, which held a hearing on his nomination over the objection of Republicans.

The allegations have complicated the administration’s nomination of Mayorkas to be second-in-command at DHS. They could also pose difficulties for Democratic Virginia gubernatorial candidate Terry McAuliffe, who co-founded the electric-car company involved in the case, and for former secretary of state Hillary Rodham Clinton, whose brother, Anthony Rodham, was involved in lobbying for the visas.

Mayorkas testified that he met with McAuliffe about twoyears ago to hear complaints about the pace of visa approvals for foreign investors at the car company, called GreenTech Automotive. He said such meetings were common and he considered them part of his job.

“I listened to his complaint and went back to my work,” Mayorkas said. “I enforce the law based on the facts. I do not put my finger on the scales of justice.”

The McAuliffe campaign did not immediately respond to a request for comment Thursday. A McAuliffe spokesman earlier this week said the inspector general’s probe “does not involve Terry” and dismissed attacks by his Republican opponent, Virginia Attorney General Ken Cuccinelli II, as a distraction.

Republicans had called on Democrats to delay Thursday’s hearing, but Chairman Thomas R. Carper (D-Del.) refused, saying in a statement that he would not allow “rumor, speculation, and innuendo to rule the day.” Carper said Mayorkas had never been notified that he was the subject of a probe.

“The Office of Inspector General apparently does not have any ‘preliminary findings’ regarding Mr. Mayorkas,” Carper said in prepared remarks prior to the hearing. “In fact . . . the Office of Inspector General has found no wrongdoing by Mr. Mayorkas.”

The donnybrook over Mayorkas is relatively unusual for the homeland security committee, which has a reputation for maintaining traditional Senate comity in era of partisan rancor. Carper, who took over the chairmanship this year, has had relatively cordial relations with the committee’s ranking Republican, Oklahoma Sen. Tom Coburn. Each refers to the other by their shared initials, “T.C.”

GOP members of the committee were not present as the hearing got underway Thursday morning, a signal they may be boycotting the event in protest. Coburn sent a statement objecting to holding a hearing while an investigation is ongoing.

If confirmed as second-in-command at DHS, Mayorkas, now director of U.S. Citizenship and Immigration Services, would temporarily lead the department after the scheduled departure of Homeland Security Secretary Janet Napolitano in early September.

“I believe it would actually be irresponsible to leave the Department without a permanent Deputy Secretary until the investigation is completed – especially given that, as of September 7th, we will not have in place a Senate-confirmed Secretary to run the Department,” Carper said in his statement.

The inspector general’s probe centers on the EB-5 visa program, which permits foreign nationals to enter the United States if they agree to invest $500,000 to $1 million to create U.S. jobs.

The inspector general’s office launched the inquiry last year following a tip from an FBI counterintelligence analyst concerned about the program, which is dominated by applicants from China, according to congressional aides.

E-mails show that Mayorkas’s assistance was sought in January by Rodham, who runs Gulf Coast Funds Management of McLean, which pools money from foreign citizens who want to invest in U.S. businesses as part of the EB-5 program.

Rodham and other Gulf Coast officials wrote to Mayorkas and other DHS officials asking for help with delays that they said were harming GreenTech Automotive, the firm co-founded by McAuliffe. The former Democratic National Committee chairman quietly severed his ties with the company on Dec. 1.

In his testimony Thursday, Mayorkas called the EB-5 program “controversial and extraordinarily complex,” and said he receives more complaints about it than any other program he administers. He said he made efforts to bring in other federal regulators, including experts in fraud securities law and intelligence.

“We do what the laws and the facts require and nothing more,” Mayorkas said.

Republicans said delaying Mayorkas’s hearing would have been a modest step. “We believe it is neither appropriate nor fair to consider the nomination of an individual under investigation,” the panel’s GOP lawmakers said in a Wednesday letter to Carper.

Sen. Charles E. Grassley (R-Iowa), a member of the Senate Judiciary Committee, also released more than three dozen pages of documents Wednesday citing problems with the EB-5 program and the role played by Mayorkas.

Grassley said he has learned that other federal agencies have raised national security concerns about program, which is under Mayorkas’s jurisdiction.

Pushing ahead with a confirmation hearing for a cabinet-level nominee under an inspector general’s investigation is unusual, according to Norman Ornstein, a congressional scholar at the American Enterprise Institute. “I can’t recall a case where this has happened,” Ornstein said.

In his statement, Carper said the allegations linked to Mayorkas were preliminary, that he has a strong record at DHS and has the endorsement of senior White House officials.

“I have also taken the opportunity to review Mr. Mayorkas’ FBI file, not once, but twice,” Carper said. “Nothing in my conversations with Mr. Mayorkas or in my review of his FBI file has convinced me that we should not be holding this hearing today.”