Estonian Prime Minister Kaja Kallas officially began her search on Wednesday for new partners to form a government, after her quarrelling two-party coalition collapsed last week. Kallas and representatives of her centre-right Reform Party met with the Social Democrats and the conservative Isamaa party. The prime minister said she was “cautiously optimistic” about her talks, but that it was not her decision to make, according to an Estonian radio report. Social Democrat leader Lauri Läänemets also spoke of a positive meeting and said common ground had been found. No one from Isamaa initially co…