The broadcaster announced on Friday that it would host a head-to-head debate between the prime minister and Labour leader on December 6, just days before the nation goes to the polls on December 12.
It comes after Swinson said her party would launch legal action if ITV failed to include her in its televised leaders’ debate set to be aired on November 19.
Layla Moran, the party’s education spokeswoman and Oxford West and Abingdon candidate, said it was “critical” that the TV debates had a Remain voice.
“We are the biggest, strongest Remain party fielding candidates in all parts of the UK and actually we are the only party that can challenge Labour and the Conservatives on this,” she told Sky’s Sophy Ridge on Sunday.
“We are in discussions with lawyers about what we are going to do with the ITV debate and we are also looking at court action for the BBC one too.”
Moran claimed it was “entirely possible” that Ms Swinson could be prime minister.
“I think in this election – and no-one is saying this isn’t a huge mountain to climb, no-one is pretending that it is not – but what we did see is that in the Europeans, different electoral system I get it, but we polled higher than the Conservatives and the Labour Party for the first time in 100 years.
“There is something weird happening in British politics right now – it’s showing itself in the last few months – anything is possible.
“I’m not saying it’s not a stretched target, it is, but for once I actually genuinely think that it is possible.”