Former finance minister AMA Muhith has said his successor faces three major challenges: increasing the size of the national budget, realising more revenue and improving the banking sector. “The most important thing is to increase the size of the budget in line with the GDP,” Muhith said during an interview with The Daily Star at his Banani residence in the capital recently.  The observation comes at a time when Finance Minister AHM Kamal is preparing to unveil his first budget on June 13.