Many MPs will be standing down at the next election
MPs will next week get a chance to debate whether there should be an immediate general election.
The SNP and Plaid Cymru are tabling a motion calling for the dissolution of Parliament.
The two parties say MPs have lost their authority after the expenses crisis and there should now be a general election.
Prime Minister Gordon Brown has rejected repeated Tory and Lib Dem calls for an election saying he wants a chance to sort out the expenses system.
The nationalists' announcement comes two days before the European and English local elections and in the wake of a damaging series of revelations about MP expenses claims.
Their motion will be the first time MPs will have a chance to formally express their support for an election and could increase the pressure on Mr Brown to go to the country.
The Liberal Democrats have said they will support the motion as they "would support any measure which would bring that forward."
The SNP and Plaid are stressing that it is not a motion of "no confidence" in the government but that it could spark a general election if enough MPs supported it when it is debated next Wednesday afternoon.
Plaid Cymru's leader at Westminster, Elfyn Llwyd, denied it had no chance of succeeding, given Labour's majority of 63.
He told the BBC News Channel: "The Conservatives are in favour of an immediate general election, the Liberal Democrats likewise and several of the smaller parties and there are many disillusioned people, if I can use that word, on the Labour benches as well.
"The immediate effect were it to succeed would be a general election. We are trying to do that because we believe the legitimacy of Parliament has long gone. People have got no faith in this institution and, therefore, it is wrong that they are governed by it."
But he said it was equally important to have a "full debate" on the issue.
The SNP's leader at Westminster, Angus Robertson, said: "This dissolution motion is about confidence in the whole Westminster political system which has been mired in the expenses scandal.
"It is not just the UK government that is out of step with public opinion, but Parliament itself.
"The only way to sort this mess out is for Parliament to be dissolved and for the people to have their say in a general election."
He said the Westminster government was "crumbling and its authority has drained away" and there were a "raft of issues" beyond expenses, such as "more responsibility for the Scottish Parliament, to reforming the House of Lords" that need to be debated by the public.
Tory leader David Cameron has called for the prime minister to hold an election in late July or early September to give voters a chance to get rid of MPs caught up in the expenses scandal.
But Mr Brown is expected to hold on until next year. The latest date he can hold a poll is in June 2010.
Asked at the weekend if there would be an early poll, Mr Brown said: "I think what people want is to clean up the system first."
The last Labour government was brought down by a Conservative "no confidence" motion in 1979 after the SNP withdrew support for the government, although the then Prime Minister James Callaghan did not have a working Parliamentary majority, unlike Gordon Brown.