ISLAMABAD, March 23: Former Pakistani president Farooq Leghari would form a political party to challenge those led by Prime Minister Nawaz Sharif and Opposition leader Benazir Bhutto."It will be a party with a difference," he told reporters here yesterday, saying its formation would be announced within two to three months.Leghari, who resigned as president in early December after losing a constitutional tussle with Sharif, accused both him and Bhutto, whom he sacked as Prime Minister in November 1996, of wrong doings and said his party would have different agenda.