[2] Sienkiewicz was one of the politicians at the centre of the tape scandal that occurred in Poland in the summer of 2014 when many of the key figures of the Polish political scene were covertly recorded in private.

[10] However, the district prosecutor's office in Warsaw launched an investigation in August 2014 to establish if Belka and Sienkiewicz had exceeded their authority.

[11] Sienkiewicz resigned along with the entire government following the election of Donald Tusk as the new President of the European Council and did not enter the new cabinet headed by Ewa Kopacz.

In the 2019 elections, Sienkiewicz won a seat in the Ninth Sejm, having run as the leader of the Civic Platform list in the Kielce district and receiving 35,009 votes.

[14] The move was met with criticism and accusations of illegality by the dismissed management and the opposition Law and Justice party, causing a parliamentary intervention in the TVP headquarters.