WASHINGTON — Top congressional Democrats are demanding that the Department of Homeland Security’s inspector general hand over information on deleted Secret Service text messages related to the Jan. 6, 2021 attack on the Capitol, accusing him of using delay tactics to stonewall their investigation.

In a letter released Tuesday, the leaders of the House Oversight and Homeland Security committees signaled they are willing to subpoena Inspector General Joseph Cuffari if he does not comply with their requests.

The lawmakers are pressing for Cuffari to provide records and testimony about alleged efforts to cover up the erasure of Secret Service communication related to the Jan. 6 attack. They also want Cuffari to recuse himself from the department’s internal investigation into the handling of the texts.

“Your obstruction of the Committees’ investigations is unacceptable, and your justifications for this noncompliance appear to reflect a fundamental misunderstanding of Congress’s authority and your duties as an Inspector General,” House Oversight Chair Carolyn Maloney and Homeland Security Chair Bennie Thompson wrote in the letter.

“If you continue to refuse to comply with our requests, we will have no choice but to consider alternate measures to ensure your compliance,” they wrote.

The renewed request comes one week after Cuffari told the committee that he would seek a legal opinion before he would provide internal documents about his office’s ongoing investigation or make his staff available for transcribed interviews with lawmakers.

“Sharing information about ongoing criminal investigations could impact potential witnesses or others who may be involved in the investigative process,” Cuffari wrote in an Aug. 8 letter to the two committees. “To protect the integrity of our work and preserve our independence, we do not share information about ongoing matters, like the information you requested in your letters.”

It’s just the latest back-and-forth over the text messages since mid-July, when Cuffari sent a letter to Congress disclosing that Secret Service text messages sent and received around Jan. 6, 2021, were deleted despite requests from Congress and federal investigators that they be preserved.

Since then, the two House committees say they have obtained evidence that shows the inspector general’s office first learned of the missing Secret Service text messages as part of its investigation into the attack on the U.S. Capitol, in May 2021. They say emails between top Homeland Security IG officials show the agency — which oversees the Secret Service — decided to abandon efforts to recover those text messages in July 2021, nearly a year before they first informed Congress they were erased.

Lawmakers want answers to why watchdog officials chose “not to pursue critical information from the Secret Service at this point in this investigation,” and only decided to renew their request to DHS for certain text messages more than four months later in December 2021.

The erasure of the messages has raised the prospect of lost evidence that could shed further light on then-President Donald Trump’s actions during the insurrection, particularly after testimony about his confrontation with security as he tried to join supporters at the Capitol. There are now two congressional probes into the Secret Service and DHS handling of those communications.

The missing texts are also at the center of the House committee investigating the Jan. 6 attack, of which Thompson is the chairman.

The Secret Service has since turned over a large number of records and documents to the committee investigating the Capitol insurrection, but only one text message between agents on the day before the attack and as a mob of rioters breached the Capitol building on Jan. 6.

The Secret Service has insisted that proper procedures were followed. Agency spokesman Anthony Guglielmi said last month that “the insinuation that the Secret Service maliciously deleted text messages following a request is false.”

Maloney and Thompson told Cuffari that his “failure to comply with our outstanding requests lacks any legal justification and is unacceptable.”

They gave his office until Aug. 23 to provide “all responsive documents” and make personnel available for interviews before lawmakers issue a congressional subpoena.