Aontú has told RTÉ that if it does not include the party in Monday's televised leaders' debate it will take court action.
RTÉ has responded to a legal letter from the party and explained its criteria for selecting the seven parties that will take part in the debate, which will be hosted by Claire Byrne in Galway next Monday night.
Aontú said this afternoon that it will consider going to the High Court on Monday morning.
There it will seek Aontú's inclusion or the postponement of the debate in order to allow all leaders to participate at a later stage.
"We have received more votes than the Social Democrats in the by-elections. We are just one Dáil seat behind them. We received more votes than People Before Profit in the locals and the by-elections," Aontú Leader Peadar Tóibín said.
Other registered parties which will not be part of Monday's debate include Independents4Change and the Clonmel-based Workers and Unemployed Action group.
Aontú has 26 candidates running in Election 2020.
"It is in the public interest that voters will hear the policy platform of all parties," Mr Tóibín said.