sentences:  From 1999 to 2007 the party remained firmly in opposition in Wales, opposed to forming an alliance with other political parties.This changed in 2007 when the Welsh Conservatives were briefly involved in coalition talks after the indecisive 2007 election on a "rainbow coalition" with the Welsh Liberal Democrats and Plaid Cymru which collapsed after the Liberal Democrats backed out.Plaid Cymru ruled itself out of having a coalition with the Conservatives on an ideological basis.