[14] The party formed a government after the 1990 Bulgarian Constitutional Assembly election but was forced to resign after a general strike that December.

[15] After two full terms out of power (1997–2001), the BSP-led Coalition for Bulgaria won the 2005 Bulgarian parliamentary election with 31.0% of the vote but without a governing majority, and formed the Stanishev Government, headed by the prime minister and BSP chairman Stanishev, with the centrist and social-liberal parties National Movement Simeon II and the Movement for Rights and Freedoms (DPS), respectively.

[15] The governing BSP-led coalition lost millions of euros of financial aid in the wake of allegations of widespread political corruption.

The cabinet was also unable to react to the encroaching global financial crisis of 2007–2008 and its term ended with a budget deficit after several successive surplus years.

The appointment of the controversial media mogul Delyan Peevski as head of the state security agency DANS sparked large-scale protests on 14 June.

[19] The protests ended when the prime minister Boyko Borisov resigned, but results after the April 2021 Bulgarian parliamentary election proved to be fragmented.

[33] Some news outlets, such as Novinite,[34] The Wall Street Journal, and The Washington Post, have described its orientation as soft Russophilia.

[35][36][nb 3] Many party leaders opposed the Istanbul Convention because they were against educating children about sexuality if it also meant same-sex relationships, and after a long debate decided to vote against it, despite internal division about it.

The party under Videnov opposed what was perceived as the strong political and economic over-reliance on the United States, and instead sought to foster more friendly relations with the neighbouring PASOK-ruled Greece and SPS-ruled FR Yugoslavia.

[54] Sergey Stanishev was noted in his policy shift away from the traditional understanding of the left, and toward a more pro-Western, pro-European and social-liberal worldview.

Having formed what was dubbed a 'liberal' tripartite coalition, he signed the accords for Bulgaria's entry into the European Union and NATO, while also implementing economic reforms that were criticised as being neoliberal and contrary to socialism,[55][56] such as the flat tax that replaced progressive taxation in the country.

Following the end of his chairmanship, the party adopted what was popularly dubbed the "anti-Stanishev amendment", which effectively barred him from returning to this position in the future.

[60][61] However the unpopularity of the government led to a major decrease in support for the BSP, due to its association with the pro-Turkish Movement for Rights and Freedoms and nationalist Attack.

The socialists even nearly managed to win the position of Mayor of Sofia, with the party's candidate Maya Manolova narrowly losing out to the incumbent Yordanka Fandakova.

However and much more controversially, around this time Ninova began to shift the party's orientation toward traditionalism and social conservatism, advocating against same-sex marriage and the Istanbul Convention, as well as taking a harsh stance against perceived 'gender ideology'.

In August 2023, BSP leader Korneliya Ninova highlighted her party's role in amending Bulgaria's Protection Against Domestic Violence Act, asserting that the changes uphold the Constitution.

The amendment, adopted during an extraordinary parliamentary session, sparked debate on gender inclusivity and was met with criticisms regarding the timeline of protection.

[81] Following the meeting of the National Council, it was announced that MP Atanas Zafirov was elected as acting Chairman, with a majority of 104 votes.

[83] In his first official statement, Zafirov denied the fact that a coup had taken place and promised to carry out fair elections for leadership positions within the party.

[86] Metodiev, a former head of the SDS Youth Wing in the early 2000s, was seen as a close advisor to the parties former leader, Korneliya Ninova.

For one, the Control Commission officially decided that Korneliya Ninova could not contest the upcoming Chairperson elections, as she had already served two terms in that capacity.

[88] The Control Commission further repealed the removal of Ivan Takov as head of the Sofia City organisation of the party, thus officially restoring him to that position.

[90] For their part, the new leadership intensified efforts to create a new left-wing alliance which would include political projects formed by dissident BSP members.

This effort culminated prior to the annual rally of the Bulgarian Socialist Party at Buzludzha, where the formation of such a left-wing alliance was announced.