House Republicans advanced two articles of impeachment against Homeland Security Secretary Alejandro Mayorkas to the Senate, launching a trial over the alleged refusal of the senior Biden administration official to enforce federal immigration law.

United States Customs and Border Protection has encountered more than 7.5 million individuals entering the country illegally since President Joe Biden assumed office. Members of the House Homeland Security Committee proposed articles of impeachment earlier this year asserting that Mayorkas has “repeatedly violated laws enacted by Congress regarding immigration and border security,” thereby enabling the considerable numbers of illegal aliens to enter the nation.

The two articles of impeachment were read on Tuesday in the Senate and lawmakers were sworn in as jurors on Wednesday. Senate Majority Leader Chuck Schumer, a Democrat from New York, remarked on the floor that the proceedings would be the “least legitimate, least substantive, and most politicized impeachment trial” in the history of the United States.

“The charges brought against Secretary Mayorkas fail to meet the high standard of high crimes and misdemeanors,” he said, urging the dismissal of the charges. “To validate this gross abuse by the House would be a grave mistake and could set a dangerous precedent in the future.”

Mayorkas is the first Cabinet official to be impeached in nearly 150 years. Members of the House narrowly voted two months ago to impeach him and advance the charges to the Senate.

Republicans nevertheless asserted that Mayorkas needed to be impeached and that the charges required meaningful consideration. “The Senate has a constitutional duty to hold an impeachment trial,” Kansas Republican Senator Roger Marshall commented in a statement. “Any diversion from this responsibility by Senate Democrats would set a dangerous precedent.”