Donald Tusk (tōōsk), 1957–, Polish political leader, prime minister of Poland (2007–14), b. Gdańsk. After studying history at Gdańsk Univ., he became active in the Solidarity movement in the 1980s. He co-founded a party (the Liberal Democratic Congress) that emerged from Solidarity, which later merged into the Freedom Union, of which he became deputy chairman. In 2001 he co-founded the Civic Platform party, and after the 2001 elections Tusk became (2001–5) deputy speaker of the Polish parliament. In 2005 his party lost in the parliamentary elections to the Law and Justice party headed by Jarosław Kaczyński, and he was defeated in a bid for the presidency by Lech Kaczyński. An advocate of free-market policies, Tusk led the Civic Platform to victory in the 2007 parliamentary elections and became prime minister of a coalition government; the party was returned to power in 2011. In 2014 he resigned as prime minister after he was chosen to succeed Herman Van Rompuy as president of the EU's European Council.