On 15 August 2010, the party announced plans to merge with the larger Democratic Alliance as part of a plan to challenge the governing African National Congress (ANC). The party disbanded as a separate political organization in 2014.
Ahead of the national elections in 2009, the ID launched a manifesto promising that, if elected to power, they would increase the staffing of the South African Police Service to 200,000, enlist 5,000 caseworkers to operate in crime-stricken communities, make South Africa a leader in renewable energy and finance a minimum social grant by taxing luxury goods, tobacco and alcohol. In addition they vowed that an "ID government would fire a minister whose department received a qualified audit two years in a row."
In 2010 ID leader Patricia de Lille formalized an agreement to merge with the Democratic Alliance. The two parties will be fully merged by 2014. Due to this, the ID did not contest the 2011 local elections as a separate entity, instead fielding its candidates on the DA's ballots. In February 2012 DA parliamentary leader Lindiwe Mazibuko reshuffled her shadow cabinet, which included appointing members of the ID to shadow portfolios for the first time. This was seen as a move towards strengthening the co-operation between the two parties heading towards the completion of the merger.