He defeated Staalman of the left-wing Christian Democratic Party in the second round in the district of Den Helder.

While MP, Oud also served as secretary of the VDB national board and editor of the De Vrijzinnige Democraat, the party's magazine.

In parliament Oud took a particular interest in military matters and education, and served as the party's finance spokesperson.

As minister, he was responsible for a large scale operation of budget cuts, during a time of economic crisis.

Oud led the VDB in the 1937 election and returned to the House of Representatives as chair of the parliamentary party.

In August 1939 he was offered the position of Minister of Finance in the cabinet of Dirk Jan de Geer, but declined.

Controversially, Oud did not resign after the German invasion of 1940, although he was not a member of the National Socialist Movement in the Netherlands (NSB).

In the spring of 1941 he was brutally harassed by members of the NSB, twelve party-members invaded the City Hall, gagged Oud, adorned him with Freemason-like symbols and made pictures of him.

In the same year the VDB merged with the social democratic SDAP and the left-wing Christian CDU to form the Labour Party.

The fact that he was refused a position on the party list for the Senate is generally seen as the political reason for Oud's split.

On 24 January 1948 he became one of the founding members of the liberal People's Party for Freedom and Democracy, together with Dirk Stikker and Henk Korthals, and served in its first national board as vice-chair.

When the law concerning the decolonisation of Indonesia, a very controversial issue, was voted on, the two-thirds majority was only reached because an amendment proposed by Oud ensured the support of the VVD.

In 1950–51 Oud came into conflict with the VVD's Minister of Foreign Affairs, Stikker, over the policy concerning Netherlands New Guinea.

Before the 1963 election Oud announced that he would not continue as MP; he was succeeded by the Minister of the Interior Edzo Toxopeus.

The father of this patient happened to be a journalist for the socialist paper Het Vrije Volk, which published a large In Memoriam the next morning.