A member of the European People's Party group, Kilch served on the Committee on Foreign Affairs. In addition to his committee assignments, he was a member of the Parliament's delegation for relations with Belarus.
From 2007 until 2011, Klich served as Minister for National Defence in the Republic of Poland, in the government of Prime MinisterDonald Tusk. During his time in office, Klich implemented Tusk's campaign pledge to withdraw Poland's troops from Iraq. By October 2008, he marked the end of his country's five-year partnership with U.S. forces in Iraq; Poland had been the only country other than the United States and Britain to command a full division of foreign troops in Iraq, and contingents from several other countries initially served under Polish command in a broad area south of Baghdad. Also under Klich's leadership, Poland and the United States signed a status of forces agreement that paved the way for the stationing of U.S. troops on Polish territory. Three months after the United States announced a reformulated missile-defense plan for Poland in 2010, Klich announced that an undisclosed number of American MIM-104 Patriot surface-to-air missiles would be deployed in the vicinity of Morąg, in northern Poland, just 35 miles from the Russian enclave of Kaliningrad. On 12 May 2011, Klich announced that Poland would lead a new EU Battlegroup of the Visegrád Group. In July 2011, Klich resigned after an official investigation into the 2010 Polish Air Force Tu-154 crash which killed President Lech Kaczyński and all 95 others on board concluded that mistakes by the military pilots were the primary cause of the disaster. Prime Minister Tusk clarified he did not hold Klich responsible for the crash, saying merely that the investigation had recommended swift and wholesale changes which could only be implemented by a new minister, Klich's deputy, Tomasz Siemoniak.
Klich has been a member of the Senate of Poland since the 2011 national elections and is currently the minority leader. He also serves as deputy chairman of the Senate's Committee on Foreign Affairs and as member of the Defence Committee. In addition to his role in parliament, Klich has again been serving as member of the Polish delegation to the Parliamentary Assembly of the Council of Europe since 2012. He serves on the Committee on Political Affairs and Democracy and on the Sub-Committee on the Middle East and the Arab World; in this capacity he is also the Assembly's rapporteur on Morocco. Since 2015, Klich has been serving as a member of the European Commission’s High-level Group of Personalities on Defence Research chaired by Elżbieta Bieńkowska.