Alliansen formed
In 2004 the Moderates, Centre Party, Liberals and Christian Democrats began formalising Alliansen, the centre-right coalition that would win the 2006 election and govern Sweden until 2014.
Alliansen was the centre-right bloc project that joined Moderaterna, Centerpartiet, Liberalerna and Kristdemokraterna into a coordinated electoral and governing alternative. The public symbol was the Högfors meeting in 2004, after which the parties increasingly campaigned as a coalition rather than four separate opposition parties.
The formation mattered because it changed the arithmetic before 2006. By the time of the 2006 election, Alliansen could present a government-in-waiting under Fredrik Reinfeldt, not merely a protest against Social Democratic rule.