By Linas Jegelevicius in Vilnius After securing the nomination as the European Union’s high representative for foreign affairs and security policy, Estonian Prime Minister Kaja Kallas on July 15 submitted her resignation to President Alar Karis, a statement from the presidency said. Kallas has been the country’s prime minister since 2021, heading three consecutive governments. However, after winning re-election last March, Kallas’ popularity has swiftly tumbled after she belatedly announced she was planning tax rises to bring down the country’s budget deficit, even though the economy was still…