Image copyright EPA Image caption The Capitol building on 19 January, after the riot
Prosecutors say one of the men accused of assault at the US Capitol called a police officer who responded to the incident “a bit of a pussy”.
They say he grabbed the officer “as if he was trying to physically remove her from the scene”, before throwing punches.
Before the January 19 riot, U.S. President Donald Trump had signed a controversial law ending protections for so-called Dreamers.
A group of protesters marched into the building to oppose the move.
The Senate leader, Mitch McConnell, and House minority leader, Nancy Pelosi, were targeted.
Some entered the House and Senate chamber shouting “shame”.
The four men were charged with assaulting a member of the House of Representatives and a Senate office building custodian.
The suspect did not use a weapon in the attack but his DNA was found at the crime scene, prosecutors have said.
John Dean is standing trial accused of smashing the windows of the Senate Democrats’ office and assaulting officers when they tried to arrest him.
Image copyright AFP Image caption A key witness said Ms Pelosi and Senator McConnell had been targeted
He allegedly smashed a screen window in a Senate office building when he was approached by an officer, who also tried to arrest him.
However, three others also accused of the crime said they did not know Dean, who has pleaded not guilty.
The four alleged assailants could face life in prison if convicted.
They are also facing charges related to the arrest of three other protesters, including one woman with a pair of scissors, who authorities say did not know Dean.
Dean, a former White House counsel for former president Richard Nixon, was the only one of the four to have pleaded not guilty to the assault charges.
During the plea hearing on Wednesday he said his DNA was found at the crime scene.
But he added: “What I saw was being attacked by the police, and what I did was defend myself.”
He said the fact he was wearing a vintage Philadelphia Flyers cap in the incident – which is a football/hockey team – did not mean he was linked to the group.
Image copyright AFP Image caption A member of the security detail made the arrest, prosecutors have said
The four men are also accused of beating a Guardian Angel, while throwing an apple at Mr McConnell’s wife.
Molly McGuire, 19, was said to have suffered a concussion and some dental damage, after being hit in the head with a baseball bat.
Another member of the security detail, Frank DiGiacomo, also sustained injuries, prosecutors say.
A fifth suspect, identified only as Amanda, told the court she did not know the other men accused of offences.