David Cameron is set to clash with the SNP and his own backbenchers by pushing ahead with plans to cut the number of MPs.
The Prime Minister said that proposals to slash the size of the Commons from 650 MPs to 600 were the "right approach".
However, some Tories believe that the loss of a significant reduction of seats north of the border could even lead to another Conservative wipeout in Scotland.
One said that the change could create opportunities for the party to take more than one Scottish seat at Westminster or "lead to annihilation".
"The problem is we don't know which one it will be," he added.
Widespread boundary changes, of the kind that would be required, could also spark a fightback from Tory MPs who fear losing their seats.
However, Mr Cameron has the backing of other backbenchers who believe the move will help the party win the 2020 General Election.
The plan could see the number of Scottish MPs cut from 59 to 52.
The SNP currently hold 56 out of 59 seats, while Labour, the Liberal Democrats and the Conservatives have one each.
Mr Cameron is also pushing ahead with plans for 'English Votes for English Laws' which many Scottish politicians warn could lead to them becoming 'second class' MPs.
The Conservative leader said that he was still behind a cut in the number of MPs because his party had pledged to cut the cost of politics.
But critics complain that the savings will be outweighed by the amount claimed by the new peers Mr Cameron has created since entering No 10.
Speaking at the summit in Germany Mr Cameron was questioned on whether or not he still backed the controversial plans.
He said: "On the manifesto commitment we have to cutting the cost of politics, I remain completely committed to that. I think it's the right approach and very important."
The Prime Minister also called again for a rethink on plans to give MPs a £7,000 pay rise.
However, he would not be drawn on whether or not he himself would take the money.
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