Top security officials in Congress are expected to reinstall fencing around the Capitol and authorize the use of deadly force ahead of a planned rally by far-right Trump supporters next weekend demanding the release of rioters arrested in connection with the 6 January insurrection.

The officials, however, had no plans so far to request the national guard, and were not pushing for such a request, principally because the threat assessment did not warrant their deployment, according to sources familiar with the matter.

The Justice for J6 rally on 18 September is being organized by the Trump operative Matt Braynard and his organization Look Ahead America. It is being held to demand that the justice department drop charges against nearly 600 people charged in connection with the Capitol attack which the group calls “non-violent protesters”, despite widespread violence and five deaths during the insurrection.

The Senate sergeant-at-arms, Lt Gen Karen Gibson, House sergeant-at-arms, Maj Gen William Walker, and US Capitol police chief, Thomas Manger, are expectedto approve fencing to form the backbone of their security response, the sources said.

The reinstallation of the 7ft fence as part of a perimeter that could extend to the Capitol reflecting pool will be supplemented by the authorization of US Capitol police officers to use deadly force to protect members of Congress and staff, the sources said.

Both measures were characterized to the Guardian as a move to warn against anyone attempting a repeat of the 6 January attack on the Capitol. The final recommendations are slated to be unveiled at a briefing to congressional leaders on Monday.

“We intend to have the integrity of the Capitol be intact,” the House speaker, Nancy Pelosi, said on Wednesday of measures being considered. “What happened on January 6 was such an assault on this beautiful Capitol, under the dome that Lincoln built during the civil war.”

The approval for the fence is almost certain to be granted as security officials believe it remains the most efficient method to secure the Capitol – and can serve as a dry-run for a new quick-reaction fencing contract funded in a $2.1bn security bill passed by Congress in July.

Members of the US Capitol police board weighed whether to request the national guard but the threat assessment for the 18 September rally reviewed at a series of meetings in recent days did not warrant the backstop, the sources said.

That appears to have come after allies of Donald Trump largely distanced themselves from the protest while no lawmakers – including House Republicans under scrutiny for their roles in the Capitol attack – have said they will attend.

The Capitol attack ultimately left nearly 140 police officers injured, including 15 who were hospitalized after battling to retake control of Congress from rioters who sought to stop the certification of Joe Biden‘s election victory.

One officer lost the tip of his right index finger. Others were smashed in the head with baseball hats, flag poles and pipes, while another officer lost consciousness after rioters pushed her backwards into stairs as they tried to reach the Capitol steps.

According to the union representing US Capitol police, one officer had two cracked ribs and two shattered spinal discs, while his colleague was stabbed with a metal fence stake. Four police officers who responded to the Capitol attacks have since died by suicide.

The event, for which Braynard filed a permit predicting 700 people to attend, comes as the Capitol has seen a series of troubling one-off incidents, including a man who parked a pickup truck next to the Library of Congress and said he had a bomb and detonator.