[1] Sahlin is the first female leader of the Swedish Social Democratic Party and became in 2011 the first since Claes Tholin in 1907 to leave that position without having served as Prime Minister of Sweden.

On 14 November 2010, following another electoral defeat for the Social Democrats, she announced her intent to step down as party chairman, which she did in early 2011.

Sahlin's political career began in the Swedish Social Democratic Youth League in Nacka, Stockholm County, in 1973, at the age of 16.

During this period, she openly criticized government reforms, particularly on social welfare and employees' rights, maintaining they needed to be reversed.

In October 1995, the newspaper Expressen following an investigation led by Christian Democratic Spanish-Swedish Public Auditor Carlos Medina de Rebolledo reported that Sahlin, who was then serving as Deputy Prime Minister and was widely seen as the main candidate to succeed Ingvar Carlsson as Prime Minister, had charged SEK 53,174 for private expenses on her working charge card, which was only for working expenses.

[9] A preliminary investigation was initiated by the chief prosecutor Jan Danielsson [sv], as a result of the transactions, and was closed in early 1996 when it came to the conclusion that there was no infringement.

In 1997, she was elected chairman of the European Council Against Racism and in 1998 she became the head of the Social Democratic youth education school Bommersvik.

Both Margot Wallström and Carin Jämtin received stronger support amongst local and regional party organisations.

Much of this criticism was silenced in January 2007 when the chairman of the Trade Union Confederation, Wanja Lundby-Wedin, expressed full support for Sahlin[18] as well as several powerful party districts around the country.

[23] She led the Social Democratic Party in the election of September 2010 where she failed to unseat Fredrik Reinfeldt as Prime Minister.

The Social Democrats received the lowest recorded percentage of the votes in their history but were still the largest party in Sweden by a slim margin in 2010.

Karen Jespersen, a former Minister of Integration in Denmark, commented: Cultural self-denial cannot easily be more monstrous and ghastly.

"[26] After the terrorist action in Brussels in March 2016, Sahlin, who was then serving as national coordinator against violent extremism, maintained in an op-ed that such atrocities were the fault not only of the terrorists themselves but of critics of Islam whose remarks in online chat rooms, in comments fields, and on social media "give the extremists their nourishment.

[28] On 5 May 2016, Sahlin stepped down from her position as Sweden's national coordinator against violence-embracing extremism, due to revelations by the newspaper Expressen that she had lied about her bodyguard's salary, in order to help him secure a mortgage.

The media mentioned similarities to the so-called Toblerone case of the 1990s when Sahlin was caught using her government credit card to pay for private expenses and then dodging the issue when confronted.