Following the 2000 Croatian parliamentary election, he became part of the first cabinet of Ivica Račan where he notably spearheaded the construction of motorways.

This transaction was later undone in a court of law, but Čačić had since sold or transferred his stakes in the Coning companies to a legal firm.

He succeeded Savka Dabčević-Kučar as President of the Croatian People's Party (HNS) and held the position for six years.

In the 2000 parliamentary election, the HNS won more seats in the Croatian Parliament and participated in the six-party coalition that formed the government under Ivica Račan.

Čačić was the only member of HNS in the government but was given the influential and suitable position of the Minister of Public Works, Reconstruction and Building which granted him access to many government-sponsored projects.

Čačić also helped organize the public state-sponsored housing project for young families, the first such endeavour in modern-day Croatia.

The new HDZ leadership organized a parliamentary investigation panel on Čačić's alleged misdeeds: he was accused of conflict of interest given how his old company Coning was also awarded contracts in building the Zagreb–Split highway.

In December 2006, the HDZ parliamentary investigation panel again convened and changed its previous decision, saying Čačić was indeed in conflict of interest because of twelve contracts worth 132 million Croatian kunas signed with companies with a connection to Čačić, without this connection being properly registered according to relevant law.

[10] On 8 January 2010, he caused a severe traffic accident on the M7 motorway in Hungary which resulted in the death of two passengers in the car he hit.

[12] The 2010 incident led to Čačić handing in his resignation as president of the Croatian Tennis Association, which was later refused by the federation's governing board.

[15] Croatian opposition politicians Tomislav Karamarko, Jadranka Kosor and Dragutin Lesar called for Čačić to resign; members of the ruling coalition Mirela Holy and Josip Leko expressed reservations about the issue.