By the late 1890s, he had gained a reputation in transport policy; his struggle for an eastern alpine railway and his lobbying for federal subsidies to the Rhätische Bahn's narrow-gauge system helped him win his party one of the Grisons' two seats in the Swiss Council of States in 1899.
During his tenure in the Council of States, he was given the mandate to negotiate an agreement with the Grand Duchy of Baden regarding the usage of the Rhine for ship transport and hydropower.
In his function as president, he was faced with increased expression of social grievances by the working class and poor, and started meeting with the "Oltener Aktionskomitee" (OAK) in August 1918.
The OAK was a committee of Swiss labor unions and Social democrats, formed to demand and enforce socio-political reforms, and led by Robert Grimm.
The OAK recognized the strike's futility, and called for its ending, Calonder informed the Federal Assembly with the words "The nightmare has gone away.
On the other hand, put under pressure by the army command and centre-right parliamentarians, he signed the Federal Council's ultimatum addressed to the OAK one day later.
In his final year in the Federal Council, Calonder was a proponent of Woodrow Wilson's idea for a League of Nations, and appointed historians and legal experts to study questions of international law in the aftermath of World War I.
With the support of fellow councillors Giuseppe Motta and Gustave Ador, Calonder finally succeeded in passing the bill to join the League of Nations against strong opposition by politicians from German speaking rural and conservative cantons, but also against the majority of Social Democrats.
He met fierce opposition within the Federal Council, namely by Schulthess and Motta, and was eventually forced to abandon his advancements in this direction.
His actions during the nationwide strike, his advancement of membership in the League of Nations, and his weak position in the Vorarlberg question resulted in a meager count of votes for Calonder's reconfirmation by the Federal Assembly in December 1919.