SNP Westminster leader Ian Blackford has signalled his party wants to see votes for 16 and 17-year-olds and for EU nationals in any forthcoming general election.
Mr Blackford told the Commons his party was "ready for an election", but "not ever on the Prime Minister's terms".
Speaking in the Commons, the MP for Ross, Skye and Lochaber warned the Labour Party "don't be the handmaidens of the Prime Minister's Brexit".
Mr Blackford said the party would not back the motion for a December 12 election but would support efforts for a December 9 poll.
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He said: "If we enable this motion to pass, we will be out before the Prime Minister's election. We cannot allow the Prime Minister to railroad through this disastrous so-called deal."
Mr Blackford added: "We will support the Liberal Democrats' proposals for an election before Brexit can happen, with no reintroduction of the Withdrawal Agreement Bill.
"Because given the way that some Labour MPs voted, we cannot trust Labour to block the Bill in future."
He went on: "It's not an issue of three days between election dates, it's an issue of whether we are in the EU or out of it, that is fundamental. We are ready for an election, but it must be on those terms, not, not ever on the Prime Minister's terms.
"In that election, we want to see votes for 16 and 17-year-olds and for EU nationals and when the election comes, we will fight the Tories on Brexit, on the rape clause, on austerity, on the harm they have done to people's lives or livelihoods and yes, we will fight them on the right of Scotland to choose our own future rather than be dragged through this Westminster mess ever again."
Mr Blackford issued an appeal to Labour to co-operate, adding: "It is about the opposition parties coming together and taking the keys of Number 10 Downing Street away from a Prime Minister that we can't trust.
"So my message to the Labour Party is, 'Let's face an election, let's do it on our terms, let's make sure that we take the Prime Minister and his toxic Tory Government out of office'.
"We can do it if the opposition unite together and we can stop the deal that the Prime Minister wants to drag through."
Intervening, Tory former party leader Iain Duncan Smith asked if any election "would be conditional on 16-year-olds being on the ballot paper and EU citizens".
Mr Blackford replied: "It is the right thing to do, that our young people have a right to have a say on their future as it is for EU nationals, that is the principle position that we have long taken."
He added: "We need to make sure that an election happens on our terms, that is the priority. It is the priority that we make sure that we legislate in future, that our young people, that our EU nationals are given due respect, but the priority that we face in the short term is to make sure that we come together, that we can stop this damaging Brexit that the Prime Minister wants to put through."