Switzerland's largest party, the populist rightwing anti-immigrant Swiss People's Party, is set for a record win in Sunday's parliamentary election, with media projecting it will take a third of seats in the lower house.

Based on final vote counts in half of Switzerland's 26 cantons, and partial counts in 11 others, the ATS news agency projected the party would take 11 additional seats in parliament.

That would give it 64 of the 200 seats in the lower house, beating its previous record high of 62 seats after the 2007 election.