Four political parties — the Pushpa Kamal Dahal-led CPN-Maoist Centre, Madhav Kumar Nepal-led CPN-Unified Socialist, Upendra Yadav-led Janata Samajwadi Party-Nepal and Netra Bikram Chand-led Communist Party of Nepal officially announced the formation of Socialist Front at a programme here today, pledging to achieve the goals of socialism under the current democratic, republican and federal system.