Hoop initially worked as the attaché and chargé d'affaires at the Liechtenstein legation in Vienna and then in the Swiss customs administration before being elected as prime minister in 1928.

Starting from 1933, he faced numerous domestic and foreign challenges to the country, notable events such as the Rotter kidnapping, 1937 spy affair and 1939 putsch.

During World War II, Hoop considered friendly, non-binding, non-provocative diplomacy to be appropriate towards Nazi Germany, supplemented by courtesy gestures and successfully maintained the country's neutrality.

This led to Hoop being criticized in a letter by prime minister Gustav Schädler, as Liechtenstein's government had already agreed to be represented diplomatically by Switzerland.

[9][10][11] Early elections were called after Johann II forced the government of Gustav Schädler to resign in June 1928 as the result of an embezzlement scandal at the National Bank of Liechtenstein.

[12] The 1928 Liechtenstein parliamentary election resulted with a win for the Progressive Citizens' Party and Hoop was appointed to serve as prime minister.

[1] Notably, he campaigned for the construction of the Liechtenstein inland canal, which was intended to bring employment and an increased amount of arable land to the country.

He approved of Hoop's efforts to bring employment to the country and gave the Landtag of Liechtenstein relative freedom to pass laws.

[20] However, an area of contention between Liechtenstein and Nazi Germany arose with Alfred and Fritz Rotter of Jewish background, who had previously succeeded in being naturalized in 1931.

[21] Hoop attempted to use private contacts and offered informal support to the German government, where he considered appealing to Otto Meissner in order for the press attacks to end.

[27] As a result, Hoop ordered a search of the offices of the Vaterland for any incriminating letters and Vogelsang promptly left the country.

[28][29] A majority of the Landtag approved of Hoop's actions, but members of the Patriotic Union called for his resignation over the issue, believing the search to be unconstitutional.

[33][34] Shortly afterwards, under the initiative of Franz Joseph, the Progressive Citizens' Party and Patriotic Union started negotiations for the formation of a coalition government.

[35] Hoop agreed to allow the Patriotic Union to enter government and for the introduction proportional representation to Liechtenstein, despite it being rejected via referendum three years prior.

[37][38] Under this coalition, deputy prime minister Anton Frommelt, a member of the Progressive Citizens' Party, was succeeded by Alois Vogt of the Patriotic Union.

[48]From 2 to 3 March 1939, Franz Josef, Hoop and Alois Vogt paid an official visit to Berlin where they met Adolf Hitler and Joachim von Ribbentrop in which they discussed safeguarding Liechtenstein's independence and neutrality while maintaining good relations.

[50] Throughout World War II, Hoop considered friendly, non-binding, non-provocative diplomacy to be appropriate towards Nazi Germany, supplemented by courtesy gestures.

[1] However, Swiss distrust of Liechtenstein's official stance grew, primarily due to the actions of the VBDL, and demanded that Hoop's government publicly declared its allegiance to Switzerland, which it did on 5 November 1940.

[1] This was primarily motivated by Franz Joseph re-opening the Swiss embassy in Bern in 1944 against the wishes of Hoop's government and the Landtag.

[1][56] In September 1945, after seventeen years as prime minister, Hoop formally resigned due to a worsening heart condition and his desire to move on from the role.

[10][57] He also remarked that Franz Joseph II had pressured him to do so, as the prince believed that post-war Liechtenstein required a change in leadership.

[55] This belief stemmed from an ongoing diplomatic crisis involving the pro-Axis First Russian National Army led by General Boris Smyslovsky, which had taken refuge in Liechtenstein a few months prior.

[10][57] In 1946, Hoop testified as a witness against the leaders of the German National Movement in Liechtenstein after they were charged for the 1939 coup attempt.

[40][63] Hoop, a habitual smoker throughout his adult life, died on 19 October 1959 due to heart failure following a surgery, at the age of 63 years.