Following World War I, Daszyński cofounded the Polish National Committee, and for a few days served as head of the Provisional People's Government of the Republic of Poland formed in the city of Lublin on 7 November 1918.

From July 1920 to January 1921 he served as deputy prime minister in a Government of National Unity led by politician and diplomat Wincenty Witos.

Ignacy Daszyński was born on 26 October 1866 in Zbaraż in the Kingdom of Galicia and Lodomeria (now in Ternopil Oblast), which, following the Partitions of Poland, was then a part of the Austrian Empire.

Soon he started to write for the leftist biweekly Gazeta Naddniestrzańska (Dniester Gazette), in which he wrote about the hard conditions of workers employed by the petroleum industry in Stanisławów and Drohobycz.

The brutality of the sinister rascals who were then making their careers in Drohobycz was so evident and public that you did not have to be a socialist to hate their felonious "production" based on the natural treasures of Mother Earth and on the unbridled exploitation of several thousand peasants who dug up the mineral wax in Borysław.

On the night of 2–3 May 1889, he was arrested by the Russian police and spent six months in jail in Pułtusk because he was mistaken for his older brother Feliks, who was engaged in the socialist movement abroad (he attended the Congress of the Second International in Paris).

He collaborated with Ukrainian socialist activists and attended the founding meeting of the Ruthenian-Ukrainian Radical Party (Rusko-Ukraińska Partia Radykalna), where he met the poet Ivan Franko.

In early 1892 he went to Lwów, where he played an important role in the first convention of the Polish Social Democratic Party of Galicia (I Zjazd Galicyjskiej Partii Socjalno-Demokratycznej).

The first steps to achieve this aim were to be democratization of the election procedures (liquidation of privileges of the bourgeoisie) and introduction of an eight-hour working day.

Later he attended the Third Socialist Congress of Galicia and Silesia and published another brochure, Bankructwo demokracji galicyjskiej ("The Bankruptcy of Galician Democracy"), in which he strongly criticized the bourgeoisie.

In the autumn of 1896, the Polish Minister-President of Austria, Count Kazimierz Badeni, introduced a partial reform of the electoral law, such that 72 members of parliament were to be elected through a form of universal male suffrage.

On 2 February 1905, after the outbreak of the 1905 Russian Revolution, he took part in a demonstration on Kraków's Market Square, during which he burned a portrait of the Tsar.

In November 1912, the PPS Revolutionary Faction and the PPSD joined the Temporary Commission of Confederated Independence Parties (Tymczasowa Komicja Skonfederowanych Stronnictw Niepodległościowych).

After the creation of the Supreme National Committee by the parliamentary Koło Polskie (Polish Circle), Daszyński became one of the members of the Executive Department.

On the one hand, he was pleased that the act proclaimed Polish statehood; on the other, he felt angry that it ignored the issue of the Russian partition of Galicia.

Other members of the government included Wincenty Witos, Tomasz Arciszewski, Jędrzej Moraczewski, Stanisław Thugutt, and Colonel Edward Rydz-Śmigły as military commander.

The government's manifesto called upon workers and peasants to take power into their own hands and build "the edifice of an independent and united People's Republic of Poland", in which all citizens would enjoy equal political and civil rights, especially freedom of conscience, speech and assembly.

Within the framework of improving social conditions, there were promises of an eight-hour working day in industry, trade and craft, and of the nationalization of mines and large estates.

In a letter published the next day, Piłsudski thanked him for his "truly civic work" in helping to create the first Polish government and for not hesitating "to sacrifice himself for the good of the cause in order to reach an agreement among divergent factors".

"[4] 36 members of the PPSD and PPS entered the Sejm and created a parliamentary group named Związek Polskich Posłów Socjalistycznych ("Union of Polish Socialist MPs").

The socialist leader contributed to the democratic character of the constitution, for example by resisting the proposal of the conservatives that members could be appointed to the Polish Senate according to their position, without being elected.

On the inauguration day of the president-elect, Daszyński and Bolesław Limanowski were attacked on their way to the ceremony by right wing fighting squads, and forced to barricade themselves inside a house.

[3]: 447 After the assassination of President Narutowicz by Eligiusz Niewiadomski, a supporter of the National Democracy movement, the socialists planned to take revenge on right wing activists.

It is high time we brought it to balanced and harmonious cooperation between the legislature and the executive[6]On 10 November 1926, at the suggestion of Daszyński, CKW PPS took a "factual-oppositional" position towards the Piłsudski government and authorities.

On 20 December 1926, after a stormy debate, the PPS General Council took a similar position, indicating that: The PPS opposition does not aim to overthrow Prime Minister Pilsudski but to reconstruct his cabinet by removing monarchist and reactionary elements and to change economic policy, which is the demand of the working class; moreover, to change internal policy, especially as far as national minorities are concerned.

On 27 March 1928, at the first meeting of the parliament, Daszyński defeated Kazimierz Bartel, the representative of the Nonpartisan Bloc for Cooperation with the Government (BBWR), and Aleksander Zwierzyński of the Popular National Union in the election for the Speaker of the Sejm.

After his election, Daszyński renounced his party functions as chairman of the PPS General Council and editor-in-chief of Pobudka, but continued as head of the Board of the TUR.

Despite this, in June 1928 Daszyński met Piłsudski with a proposal to form a coalition of the BBWR, the PPS and the Polish People's Party "Wyzwolenie" (PSL "Liberation").

On 29 March 1930, under pressure from members of the BBWR, Daszyński withdrew the Czechowicz case from debate in order not to escalate the conflict with Piłsudski.

Daszyński stood up for the detainees, sending an open letter to Irena Kosmowska, an ex-member of PSL "Liberation" who was being held in Lublin Castle.