In 1998, Kalousek was elected as MP on the ticket of the Christian Democrats, the party he led from 2003 until his departure in 2006. The 2006 parliamentary election resulted in a situation where no party or coalition of parties was able to form a viable government. Over a period of many months a number of alternatives were negotiated with no result. On 24 August 2006 Kalousek unexpectedly accepted an offer from Jiří Paroubek to start negotiations on a minority government of KDU-ČSL and the Social Democratic Party which would be supported by the Communists. The presidium of the party expressed no objections. Such negotiations were in conflict with the pre-election promises and the vocal anti-communist stance of the party and its electorate. On 25 August 2006 mass protests by KDU-ČSL members, regional organisations and members of parliamentwent public. The party group in Brno rejected the negotiated solution and asked for the resignation of Kalousek and of the whole presidium of KDU-ČSL. Other organisations made similar demands. Some members of parliament declared that they would refuse to support such a government. On the evening of the same day the country-wide committee of KDU-ČSL refused the proposal by an overwhelming majority and Kalousek resigned. He has claimed his negotiation with Jiří Paroubek was part of a plan to prevent a government coalition of ČSSD and the Civic Democratic Party, which otherwise seemed to be the most likely scenario. That goal in fact came to pass when ODS refused to participate in a "grand coalition" and created its own government with minority support in the Parliament. In 2007, Kalousek was appointed as a Finance Minister in the cabinet of Prime Minister Mirek Topolánek, a position he held until 2009 when Topolánek's cabinet lost a vote of no-confidence. In 2009, Kalousek and Karel Schwarzenberg co-founded a pro-European, center-right and conservative political party, TOP 09, that found success in the 2010 legislative election and the party formed a coalition government with the Civic Democrats and Public Affairs, a move that secured the Ministry of Finance for Kalousek for the second time. Kalousek was re-elected as MP in the 2013 legislative election but lost the post of Finance Minister. In 2015, he was elected as Leader of TOP 09, succeeding Karel Schwarzenberg.
