Despite his vow to act as a constitutional monarch who would defer to the power of the parliamentary government, Mohammad Reza increasingly involved himself in governmental affairs and opposed or thwarted strong prime ministers. Prone to indecision, however, Mohammad Reza relied more on manipulation than on leadership. He concentrated on reviving the army and ensuring that it would remain under royal control as the monarchy’s main power base. In 1949 an assassination attempt on the Shah, attributed to the pro-Soviet Tudeh Party, resulted in the banning of that party and the expansion of the Shah’s constitutional powers.