The party is all set to retain three of Wales' 40 seats in the British parliament's 650-member House of Commons and win three further target seats in a clear bid to replicate the rapid advance of their ideological soul mates in Scotland: the pro-independence Scottish National Party.
They have pledged to join forces with the SNP and the Greens to push the ruling center-right Conservatives out of power and prop up a Labor minority government.
All three parties are opposed to spending cuts to eliminate Britain's deficit — something pledged by both the Conservatives and Labor.
Plaid Cymru was formed in 1925, chiefly as a Welsh language pressure group. They won their first parliamentary seat in 1966.
Leanne Wood, a 43-year-old trenchant republican, has been in charge of Plaid since 2012.
