Brunhart was Deputy Prime Minister of Liechtenstein under the government of Walter Kieber from 27 March 1974 to 26 April 1978.

[1] The 1978 Liechtenstein general election resulted in a win for the Patriotic Union, and Brunhart was appointed as Prime Minister.

[7] On 6 December 1992 a referendum was to be held in Switzerland on a federal resolution on the accession to the European Economic Area (EEA).

On 28 October 1992, he threatened to dismiss the Landtag and Brunhart's government over the dispute and appoint an acting prime minister in his place.

[4][14] He has been an honorary member of the Patriotic Union since 1996 and is occasionally still consulted in politics, most recently by Daniel Risch in 2022.