To be elected Pope it is not necessary to be a Cardinal, although only Cardinals may elect a Pope. The last time they elected someone not of their number – in the Conclave that elected Urban VI (born c.1318 reigned 1378-1389) — the consequences were not happy. You do not absolutely have to be a Cardinal to become Pope, but it certainly helps. George Weigel tells us how Karol Wojtyła became Cardinal-Archbishop of Kraków. Wojtyła (in case you didn't know) went on to be Pope John Paul II and an instrument in the collapse of communism in eastern Europe. He describes a conversation between the Polish regime's chief communist ideologue, Zenon Kliszko, and one of the few serving Catholic politicians. Weigel states that Kliszko was Marshall (or Speaker) of the Sejm (Parliament) but apparently at the time that was Czesław Wychech. According to Jonathan Kwitny in chapter 1 of Man of the Century, Kliszko was "minister of religious affairs" (lower case in original). (That link might not work since the New York Times has a delayed firewall: the same link should be the first result of this search). Anyway, Weigel:
In the late fall of 1963, Father Andrzej Bardecki, the ecclesiastical assistant at Tygodnik Powzechny [Universal Weekly, a Catholic newspaper], had a visitor. Professor Stanisław Stomma, head of a five-member Catholic micro-party permitted in the Sejm, discreetly asked Father Bardecki if they could take a walk on the Planty, the greensward that surrounds Kraków's Old Town and a pleasant place to talk while avoiding the secret police bugs in the Tygodnik Powzechny office. Once the two men were outside, Stomma told Bardecki that he had recently spoken with Zenon Kliszko about the logjam in filling the vacant archbishopric of Kraków. Kliszko, who did not lack ego, was very pleased with himself for having vetoed all seven names the Primate had proposed over the past year and a half. "I am waiting for Wojtyła," Kliszko said, "and I'll continue to veto names until I get him." Stomma had thanked the ideologist for sharing this confidence, but had had to work hard to keep himself from laughing. Wojtyła was precisely the candidate Stomma, his fellow Catholic parliamentarians, and priests like Father Bardecki were quietly hoping for…
Then there was the warden at the prison in Gdańsk, who at the time had a distinguished prisoner. Father Piotr Rostworowski, abbot of the Camaldolese monastery outside Kraków, was doing time for helping smuggle Czech citizens across the Czech-Polish border. When Karol Wojtyła's nomination as archbishop was publicly announced, the warden paid his prisoner a visit and gloated over the nomination. This was "very good news," he told the abbot; Wojtyła was exactly the man the comrades wanted. Four months later the warden, on another visit to the abbott, took a different line. "Wojtyła has swindled us!" he cried.
George Weigel, Witness to Hope, Harper-Collins, 1999, chapter 6, pp. 184-6.I thought of that story when I read a post by Fr Alexander Lucie-Smith at the Catholic Herald. It was about the 'White March' of 17th May 1981 organised as a show of support for the Pope after the attempt on his life on four days earlier.
People did go to huge Communist rallies in the old days, but they went, one rather suspects, because they felt they had to, rather than because they wanted to. But for John Paul, people turned out with a will. It was all organised by word of mouth, and all organised in defiance of the state. And those were the people I felt sorry for – the members of the Politburo, the high ups in the Polish United Workers’ Party: Stalin, Khrushchev and Brezhnev’s henchmen. How their hearts must have sunk when they saw half a million people turn out to pray for their Pope. For at that moment they must have seen that it was all quite hopeless, that Communism was doomed, that it never had, and never would, command people’s affections in the way the Church and Karol Wojtyla so effortlessly did.