During the Parliamentary elections of 2011, Kross ran for a seat in Parliament on the list of
Estonian Greens candidates as number one in
Pärnumaa, and number two on the all-state list of the party. He received 3579 votes – the biggest number of votes in the entire list of Estonian Greens candidates - 8,8% of all votes in his electoral district, but did not make it to the Parliament. On 5 December 2011 Kross joined the liberal conservative
Pro Patria and Res Publica Union (IRL). In January 2012 the IRL Congress elected Kross to the Executive Board of the party. He is also a member of the IRL Tallinn region board and IRL Assembly. At the local elections of 2013 Kross was the mayor's candidate for the capital Tallinn for IRL. He ran an aggressive campaign and raised the popularity of IRL in the capital from 5% in May to 20% in October. Kross received 6897 votes - the biggest number of votes for a newcomer at local elections in Estonian history - 26.4% of all votes in his electoral district. Edgar Savisaar's Center Party won the elections, Kross became a member of the City Council and the leader of the opposition in Tallinn. In October 2014 Kross left the IRL and joined the liberal democratic
Estonian Reform Party. During the
Parliamentary Elections of 2015 he ran on the Reform Party ticket in the Tallinn 3rd district and won a seat in Parliament after the MEP
Urmas Paet did not accept his mandate. In addition to his role in parliament, Kross has been serving as member of the Estonian delegation to the
Parliamentary Assembly of the Council of Europe since 2015. As member of the Estonian Reform Party, he is part of the
Alliance of Liberals and Democrats for Europe group. In 2015-2018 he was a member of the Committee on the Honouring of Obligations and Commitments by
Member States of the Council of Europe (Monitoring Committee) and the Committee on Migration, Refugees and Displaced Persons. He was also a member of a cross-party delegation to observe the
2017 presidential elections in
Serbia. Currently he is the head of the Estonian Delegation to PACE and Vice President of the Monitoring Committee. == Other activities ==