In 2009, Sassoli left his journalistic career to enter politics, becoming a member of the centre-left Democratic Party (PD) and running in the 2009 European Parliament election, for the Central Italy district.
On 7 June, he was elected member of the EP with 412,502 personal preferences, becoming the most-voted candidate in his constituency.
From 2009 to 2014, he served as PD's delegation leader in the Parliament.

On 9 October 2012, Sassoli announced his candidacy in the primaries for the centre-left's candidate as new mayor of Rome in the 2013 municipal election.
He ended up in second place with 26% of votes, behind Senator Ignazio Marino, who got 55%, and ahead of former Minister of Communications Paolo Gentiloni.
Marino would be later elected mayor, defeating the right-wing incumbent, Gianni Alemanno.

In the European Parliament election of 2014, Sassoli was re-elected to the European Parliament, with 206,170 preferences.
The election was characterized by a strong showing of his Democratic Party, which gained 41% of votes.

On 1 July 2014 Sassoli was elected Vice-President of the European Parliament with 393 votes, making him the second most voted Socialist candidate.
In addition to his committee assignments, he is a member of the European Parliament Intergroup on Extreme Poverty and Human Rights.
In 2009, Sassoli left his journalistic career to enter politics, becoming a member of the centre-left Democratic Party (PD) and running in the 2009 European Parliament election, for the Central Italy district. On 7 June, he was elected member of the EP with 412,502 personal preferences, becoming the most-voted candidate in his constituency. From 2009 to 2014, he served as PD's delegation leader in the Parliament.
On 9 October 2012, Sassoli announced his candidacy in the primaries for the centre-left's candidate as new mayor of Rome in the 2013 municipal election. He ended up in second place with 26% of votes, behind Senator Ignazio Marino, who got 55%, and ahead of former Minister of Communications Paolo Gentiloni. Marino would be later elected mayor, defeating the right-wing incumbent, Gianni Alemanno.
In the European Parliament election of 2014, Sassoli was re-elected to the European Parliament, with 206,170 preferences. The election was characterized by a strong showing of his Democratic Party, which gained 41% of votes.
On 1 July 2014 Sassoli was elected Vice-President of the European Parliament with 393 votes, making him the second most voted Socialist candidate. In addition to his committee assignments, he is a member of the European Parliament Intergroup on Extreme Poverty and Human Rights.
David Sassoli