WASHINGTON — House Oversight Committee Chair James Comer (R-Ky.) quietly sent telecom giant AT&T a subpoena last week demanding more than a decade of phone records related to President Joe Biden’s son.

The Mar. 6 subpoena, obtained by HuffPost, gave AT&T two weeks to hand over all records of user activity, including texts and call logs, relating to Hunter Biden’s accounts going back to 2011.

Comer issued the formal demand for Hunter Biden’s phone records as part of Republicans’ impeachment inquiry against the president. So far, thousands of pages of Biden family bank records and more than a dozen witness interviews haven’t revealed wrongdoing by Joe Biden.

The impeachment effort suffered a spectacular setback last month when the Justice Department announced charges against an FBI informant whose allegedly false statements served as a key piece of evidence in the case against Biden. The AT&T subpoena shows, however, that Republicans have kept digging.

Democrats on the committee, led by Rep. Jamie Raskin (D-Md.), blasted the the subpoena on Tuesday in a staff memo obtained by HuffPost. Democrats said the subpoena would encompass 15 years’ worth of records even though it asked for material since 2011.

“This subpoena for 15 years’ worth of Hunter Biden’s phone records is just the latest evidence that Republicans’ investigation, which has failed to uncover so much as a scintilla of evidence of an impeachable offense by President Biden, is nothing more than a transparent effort by the Chairman to harass the President and his family, indulge [Donald] Trump’s demands for political retribution, and amplify Russian propaganda and disinformation,” the memo says.

A spokesperson for Comer did not immediately respond to a request for comment. AT&T did not immediately respond to requests for comment.

Republicans have announced most, but not all, of the subpoenas and interview requests they’ve sent out since last year.

The subpoena specifically asked for “account information, communications, and payment history of all AT&T accounts affiliated with Robert Hunter Biden,” according to the Democratic memo, which said Comer suspects the phone records could also encompass a personal phone line used by Joe Biden when he was vice president.

Comer claims Joe Biden participated in his son’s business deals, pointing to testimony from former associates of Hunter Biden who said he would put his father on speakerphone in their company. Those same witnesses have said, however, that the elder Biden offered pleasantries and didn’t talk about business.

One specific phone call has been a major focus. Devon Archer, who served with Hunter Biden on the board of Burisma, a Ukrainian gas company, told investigators last year that Burisma officials asked Hunter Biden to “call D.C.,” in December 2015, in order to help the company. Republicans have claimed, dubiously, that the phone call resulted in then-Vice President Joe Biden pushing for the ouster of a Ukrainian prosecutor.

Hunter Biden testified last month in his own deposition that he never would have called anyone in Washington to pull strings for Burisma. “It never happened,” he said.