As a teenager, Demszky joined an informal Maoist radical group, which criticized the socialist Kádár's government from an ultra-hardliner communist viewpoint.

His main anti-government activities included the organizing of printing and publishing of illegal books, periodicals, and newspapers collectively called 'samizdats'.

[1] In the first five years they managed to bring unemployment and homelessness down by inviting private investors and building relationships with employee-trainers, but the economy of the city mainly depended on government policy.

A government denial of transferring of even compulsory funds to compulsory services of the city in the 1998–2002 term led to a stop in infrastructure investment and, in spite of the metropolitan government's own funds were diverted to repair-politics, statistical degradation of the pipe system and all materials (schools, buses, trams, heat plants) in metropolitan ownership took place for four years.

[5] His party initiated the dissolution of the central local government to district governments which had significant powers like deciding the layouts of areas on the micro-level, or deciding on allowing demolition of large areas after selling them to private investors, which in return built and paved roads and built and replaced pipes in outer districts.

In 2006, after the Ferenc Gyurcsány's audiotape-created political crisis broke out, Demszky's actions to seek ways to limit or otherwise restrict demonstrations critical of the government were criticised by his party's opposition and as well as by civil rights groups.

He ordered the posting of 100–150 signs forbidding agricultural vehicles to use Budapest's main roads and enter the city center,[6] to prevent an agricultural association staging a protest against the government and also he initiated a regulation, that mandates a permission to be obtained from the mayor's office to set up a stage for the purpose of a political event and also mandates a permission to be obtained for placing vehicles on public property for non-parking reasons.

Nevertheless, he thought that the protest had no real basis, as all fund transfers were done that year, the tractors were funded by the government 40–45%, and the leaders of the agricultural association happening to organise were members of that Fidesz faction which agitated to radicals in front of parliament, and refused to be present in the assembly during the Prime Minister's speeches, the only difference was that these members have drawn into battle their supporters' tractors also.