Republicans pounced on the discovery on Saturday of more classified documents at Joe Biden’s residence, accusing the president of hypocrisy and questioning why the records were not brought to light earlier.

Biden lawyers have discovered at least 20 classified documents at his residence outside Wilmington, Delaware, and at an office in Washington used after he left the Obama administration, in which he was vice-president.

It is not yet clear what exactly the documents are, but Biden lawyers have said they immediately turned over the documents to the National Archives. This week, the attorney general, Merrick Garland, appointed a special counsel, former US attorney Robert Hur, to look into the matter.

The materials are already a political headache for Biden. When the FBI raided Donald Trump’s Mar-a-Lago resort to obtain classified material the former president kept, Biden said: “How could that possibly happen? How anyone could be that irresponsible?”

On Sunday, Don Bacon, a Nebraska Republican, told ABC’s This Week: “It just just reminds me of that old adage, ‘If you live in a glass house don’t throw stones.’ And I think President Biden was caught throwing stones.”

James Comer of Kentucky, the new chair of the House oversight committee, told CNN’s State of the Union: “While he was doing this, he knew very well that he himself had possession of classified documents so the hypocrisy here is great.”

There is no evidence Biden was aware he had the documents. His lawyers have said they were misplaced.

Comer also noted Biden’s attorneys discovered the classified material on 2 November, days before the midterm elections, and questioned why the discovery hadn’t been made public earlier.

“Why didn’t we hear about this on 2 November, when the first batch of classified documents were discovered?” he said.

Comer has requested visitor logs for Biden’s Delaware residence from January 2021 to the present as well as additional communications about the search for documents, CNN reported.

Marc Short, who was chief of staff to Mike Pence in the Trump administration, told NBC’s Meet the Press: “Why’d they hold it? Why didn’t anybody talk about it? Is it because of the midterm elections they didn’t want to interfere with?”

Even though two special counsels are looking into how both Trump and Biden handled classified material, there are key differences between the cases.

Trump had hundreds of classified files and rebuffed government efforts to return them. The White House has said the 20 or so Biden documents were inadvertently misplaced and turned over as soon as they were discovered.

Jamie Raskin of Maryland, the ranking Democrat on the House oversight committee, told CNN: “We were delighted to learn that the president’s lawyers, the moment they found out about the documents that day, turned them over to the National Archives, and ultimately to the Department of Justice.

“That is a very different posture than what we saw with Donald Trump. He was fighting for a period of more than eight months to not turn over hundreds of missing documents that the archives was asking about.

“There are some people who are trying to compare having a government document that should no longer be in your possession to inciting a violent insurrection against the government of the United States,” Raskin added, referring to the 6 January 2021 attack on Congress Trump incited after losing the 2020 election to Biden.

“And those are obviously completely different things. That’s apples and oranges.”

The California Democrat Adam Schiff, the former chair of the House intelligence committee, praised the appointment of a special counsel in the Biden matter and said he wanted Congress to do its own intelligence assessment of the Biden and Trump materials.

But Debbie Stabenow, a Democratic senator from Michigan, acknowledged that the discovery of additional documents on Saturday was “certainly embarrassing” and that Republicans would use it as a distraction.

“It’s embarrassing that you would find a small number of documents, certainly not on purpose,” she told NBC.

Biden’s lawyers, she said “don’t think [this] is the right thing and they have been moving to correct it … it’s one of those moments that obviously they wish hadn’t happened.

“But what I’m most concerned about, this is the kind of things that the Republicans love.”