The proposal will be voted on by party members at the Lib Dem annual conference which starts on Saturday in Bournemouth.
Ms Swinson said: The Liberal Democrats are fully behind a Peoples Vote with the option to remain, and we would campaign to stay in.
We believe this is the best way to resolve the Brexit mess, and it is in the countrys best interest. However, a general election may well happen before a Peoples Vote.
I relish the chance to take the fight to Boris Johnson in an election, and Im confident wed make significant gains.
Whenever the election comes, our position is clear and unequivocal. A majority Liberal Democrat government would not renegotiate Brexit; we would cancel it by revoking Article 50 and remaining in the European Union.