Federal prosecutors have filed charges against more than 300 people in the January 6 storming of the Capitol, NBC News reports citing the US Department of Justice.
At least 280 people were arrested.
On Thursday, acting US Capitol Police Chief told Congress she was concerned that members of some groups that were involved in last month's riots might try to target US President Joe Biden's first appeal in a joint meeting.
The date of Biden's speech has not yet been determined.
When asked about the potential threat, a senior FBI official said that after the election, investigators are closely monitoring extremist groups.
She noted that they are very closely monitoring any reaction from individuals who could demonstrate either intent to attack or someone who has already committed it.
They have increased the number of lawyers and investigators working on domestic terrorism cases, according to US Department of Justice officials. Anti-government sentiment and racial or ethnic hatred are currently the two main motives for attacks by domestic extremists, the official said.