How did Koizumi Junichiro weaken the Liberal-Democratic Party’s faction system?

Koizumi Junichiro weakened the traditional factional system of the Liberal-Democratic Party (LDP) by prioritizing reformist credentials and public appeal over the influence of powerful faction bosses.1

His approach included several key strategies:

• Cabinet Appointments: Koizumi deliberately slighted traditional party factions when forming his cabinet, appointing individuals based on his reform agenda rather than factional loyalty.2
• Direct Mandate: His rise to the party presidency in 2001 was facilitated by a new voting process that included party rank and file at the prefectural level, allowing him to win by a decisive margin independent of factional control.2
• Purging Opposition: When faced with resistance to his policy goals—specifically the privatization of the postal system—Koizumi purged the LDP of members who opposed his plans, effectively challenging the internal power structures that factions traditionally protected.2
• Shifting Electoral Strategy: By targeting unaffiliated urban voters and promising to reduce pork-barrel spending, he moved the party away from the traditional koenkai (personal support organizations) system that had historically been nurtured by factional resources and local public works projects.1