By MONIKA SCISLOWSKAWARSAW, Poland (AP) â¿¿ Polish Prime Minister Donald Tusk easily won re-election as his party's leader on Friday, but his government has been losing popularity halfway through his second term in office. Tusk won about 80 percent of the votes in the governing center-liberal Civic Platform's leadership election, while challenger Jaroslaw Gowin got 20 percent, according to results released Friday. But only 51 percent of the party members voted, undermining the depth of Tusk's support. His Civic Platform party, the main one in his coalition government, is rapidly losing support, and will need to boost its image for the 2015 parliamentary election. Poland's longest-serving prime minister since the days of communism, Tusk took office in 2007, and for years he faced no serious challenge, while the economy continued to grow, despite the global crisis. But last year Poland's economy slowed down, unemployment soared to more than 14 percent, and the government is facing criticism for unpopular decisions such as raising the retirement age, cutting pension privileges for some groups, and trying to give marriage-like rights to same-sex couples, in this largely conservative Catholic nation. Observers noted that Gowin's result was higher than expected. Tusk fired Gowin as justice minister earlier this year, in punishment for his voting against the party in a parliamentary vote. On Friday he congratulated the opponent's "quite good result" and encouraged him to further cooperation in the party, against calls from some members to expel Gowin. For his part, Gowin said he was satisfied with his result and called on Tusk to work to improve his economy and social policy in support of large families. This year Tusk's government is cutting spending to counter a recently disclosed increase in the country's budget deficit, leading to speculation â¿¿denied by Tusk â¿¿that Finance Minister Jacek Rostowski will eventually have to go.