Mellat Iran was far more fervently nationalist than the former party, and strongly supported and was allied with the national movement of Mohammad Mossadegh, who had founded the National Front of Iran ("Jebhe Melli") with other Iranian nationalist leaders. The party was allegedly funded by the Central Intelligence Agency through TPBEDAMN. After the British-American sponsored coup d'etat against Mossadegh, the Shah assumed dictatorial powers and outlawed almost all political groups, including Mellat Iran and the National Front. The Pan-Iranist Party soon became the official opposition in the Majlis, with Pezeshkpour as Speaker. However, in reality, the party had very little political power and influence and its position was primarily intended to be symbolic. Beginning in the late 1960s, under the government of Amir Abbas Hoveyda, Iran mostly became a one-party dictatorship under the Imperial Resurrection Party ("Rastakhiz"). Pezeshkpour remained active in the Majlis and spoke out against British rule in Bahrain, which Iran claimed. He established a residence in the city of Khorramshahr, which at the time was home to some of the most exclusive neighborhoods in Iran, and which also became his base of operations. In Khuzestan the party was for the first time able to become a dominant influence, whereas in the rest of Iran, the party continued to have very little effect. With the onset of revolution in 1978, Pezeshkpour and other politicians who had been allied with the Shah fled the country into exile. Mohammad Reza Ameli Tehrani, a co-founder of the party, was sentenced to death by the Revolutionary Court, and subsequently executed in May 1979. Nationalist movements such as Mellat Iran and the National Front, which had been opposed to the Shah, remained in the country and played a crucial role in the revolutionary provisional government of Mehdi Bazargan. After the Islamic Revolution of 1979 which eventually saw the rise to power of Khomeini to the position of Supreme Leader after the collapse of the provisional government, all nationalist groups, as well as socialist and communist movements such as the Tudeh Party, were banned. In the early 1990s, Pezeshkpour wrote a letter of apology to the new Supreme Leader, Ali Khamenei, stating that he wished to return to Iran and promised to stay out of politics for good. Khamenei accepted the apology and allowed Pezeshkpour to return, on the condition that he not resume his previous political activities.