After Prime Minister Ferenc Gyurcsány formed his minority government, he served as a secretary of state in the Ministry of Environment and Water from 1 May 2008 to 15 April 2009.

Oláh held the position of secretary of state in the Ministry of Transport, Communications and Energy during the cabinet of Gordon Bajnai, from 21 April 2009 to 29 May 2010.

[3] During the 2010 parliamentary election, Oláh was re-elected MP via MSZP regional list of Hajdú-Bihar County, but the party itself suffered a heavy defeat against Fidesz.

When the platform split from the Socialists on 22 October 2011 he joined to newly formed party and left the MSZP and its parliamentary group.

[3] Oláh ran as a joint candidate of the Unity electoral alliance in Erzsébetváros (5th constituency, Budapest) during the 2014 parliamentary election.

[3] Oláh was re-elected MP for Erzsébetváros in the 2018 parliamentary election, defeating Fidesz candidate István Bajkai.

In the parliamentary election held on 3 April 2022, he again became the single member of the constituency, winning 20,561 votes and an absolute majority of 51.39%.