Amnon Rubinstein is no stranger to high office, but even for him the pace must have been breathtaking. In the space of a few hours on Monday, he went from being the prospective head of the governmental commission of inquiry into the war, an appointment he eventually turned down, to Kadima's preferred candidate for the presidency of the state. Both these candidacies are still unofficial, of course. They exist only in the media, but the way the investigation of President Moshe Katsav seems to be going, it might not be a bad idea to have an available candidate around. No serious candidate, of course, is going to allow his name to be put forward before Katsav resigns, but Prime Minister Ehud Olmert and his senior colleagues don't want to be caught unprepared. The successful election of a president is a litmus test of political power. The Likud, even when it was in government failed to get its candidates voted in, proving that Labor, even in opposition, remained the party of establishment. Ariel Sharon was the first leader of the Likud to succeed in placing the party's man, Katsav, in Beit Hanassi and it was seen then as one of the signs of prime minister Ehud Barak's political decline and the emergence of Sharon as a viable prime minister. In the current political climate, the last thing Olmert and Kadima can afford is to lose a snap presidential election. Winning one, on the other hand, could be an important step in reestablishing the party's credibility as a party of power, rather than a one-term wonder. Rubinstein is therefore being groomed as the perfect candidate. The only fly in Kadima's ointment is that Rubinstein isn't their first unofficial candidate. Incessant leaks to the media over the last few months have been pointing at former chief rabbi Yisrael Meir Lau as Olmert's preferred candidate. So has Lau's popularity suddenly waned or is someone playing a double game, presenting the media and public with two potential presidents, testing the water without committing. Neither Lau nor Rubinstein has said a word in public about wanting the job, but a network of Lau's admirers has been in place for a long time, preparing the ground for his candidacy. Rubinstein hasn't done any serious lobbying yet, but it's hard to believe that his name would have been put forward if he wasn't interested in the job. Both don't want to be seen as political opponents; they will only enter the fray if there's a consensus created around them. It's unlikely that either of them will announce without at least tacit backing from Olmert. So who would be the better president? The first consideration in choosing a candidate, naturally, is electability. The secret Knesset ballot has confounded expectations more than once; deals and previous loyalties don't always bind when the MK is behind a curtain - ask Shimon Peres. So the backers will be trying to create as wide a base as possible. Kadima with its 29 MKs hasn't got enough clout, but on the other hand, no other party is as powerful, so it's all going to be about ad hoc coalitions. That was the initial attraction of Lau: How could the religious and haredi parties, normally rivals of Olmert, not vote for a rabbi. Together with a smattering of secular admirers from other parties, the nomination should have been in the bag. But over the last three months, a negative reaction to Lau's putative bid began. Voices were raised, mainly but not only in the media, against a president who wouldn't shake women's hands and who would have nothing to do with Reform and Conservative Jewish leaders. Doubts also rose around the haredi support for Lau: Some haredim actually might prefer not to see one of their own as president, so as not to grow too close to the secular emblems of the state. Another consideration is exposure to scandal. After president Ezer Weizman's term ended in ignominy due to the donation he had received from a mysterious businessman, and a sex scandal is now engulfing the current president, anyone proposing a new president is going to make some serious background checks on his guy. Lau has some serious enemies within the religious world; they will be dishing out dirt on him the moment his candidacy becomes official, whether it's real dirt or manufactured, perhaps it's not worth the risk. In addition, one of the values of Lau as a president was that he could act as a go-between with the settlers Olmert was planning to remove as part of his realignment plan. Now that realignment has been suspended indefinitely, the government has different needs. Rubinstein, on the other hand, might be the man of the hour. An academic and legal heavyweight, a former dean of Tel Aviv University Law School, an MK and legislative pioneer for more than a quarter of a century, a cabinet minister in two governments and as a founder of Shinui, the Democratic Movement for Change and Meretz, he's a veteran of center-left politics, though in the last few years, he's drifted away from the left, claiming it's forgotten whose side it's on. Some of his latest books have defended Israel and Zionism against international left-wing criticism. He was careful not to align himself with any party during the last elections, but in interviews, he spoke warmly of the Kadima leadership. Rubinstein, at 72, might have the required experience and gravitas to reassure Kadima's core electorate, the secular middle class, that the party can still be relied on to run the country. Ultimately, the choice of presidential candidate will indicate where Kadima and Olmert are headed. If they still go for Lau, it means that they still think the realignment plan has a chance. If they switch to Rubinstein, it will signal that realignment is off for now and they've got to placate those who voted for another round of withdrawals.