The Knesset is going to vote for a new president on Tuesday. With five candidates in the running, the vote is widely expected to go to a runoff ballot between the two top contenders.

On Monday, we predicted a runoff round between two former speakers of the Knesset, Likud MK Reuven Rivlin and former Labor and Kadima lawmaker Dalia Itzik. Yet while predictions abound, the vote itself is secret. MKs can say one thing to the cameras — and their party bosses — and do another at the moment of decision. So the chances of the other candidates, former Supreme Court justice Dalia Dorner, Hatnua MK Meir Sheetrit and Nobel laureate chemist Dan Shechtman, cannot be ruled out.

What follows is a brief survey of the rules and procedures for the presidential vote. As any veteran politician will acknowledge, in politics procedure is at least as important as voters’ actual preferences. Our American readers might recall that Hillary Clinton won the most votes in the 2008 Democratic primary, and Al Gore in the 2000 presidential elections — yet both lost the contest because of the special way votes were being counted. In Israel, too, Tzipi Livni’s Kadima party won the most Knesset seats in the 2009 parliamentary election, but it was Benjamin Netanyahu’s Likud that cobbled together the ruling coalition.

So it is with the presidency. The clear frontrunner is Reuven Rivlin, who is almost certain to reach the runoff round. But in the second vote, Rivlin will face not four opponents to his political left, but just one. While he is likely to receive most right-wing votes in today’s vote, his victory will depend on how the votes of centrist, left-wing and ultra-Orthodox MKs divide in that second round. (Of course, he may yet surprise and draw enough votes from his political left to become president in the first round.)

The voting will begin at 11 a.m. All 120 parliamentarians are eligible to vote, though one, UTJ MK Meir Porush is traveling and will not be voting.

To win the first round outright, a candidate must receive 61 votes, a full Knesset majority. (Rivlin has some 36 public declarations of support, far more than the next in line, Dalia Dorner, with just 14.)

If the leading candidate fails to get 61 votes in the first round, the two candidates with the most votes go to a runoff round. If the leading candidates tie in the first round, the two tied candidates go together to the runoff.

If three candidates tie for first place or two candidates tie for second place — that is, if there are three frontrunners rather than two — the first round is redone until just two candidates are in the lead. Only two candidates may enter the runoff.

If one of the two runoff candidates decides to quit the race before the runoff vote, then the Knesset holds an up-or-down vote on the remaining contender. If he or she wins a majority of the votes cast, they win the presidency. If there is a tie, the vote is held again until the tie is broken.

The only scenario in which the Knesset fails to elect a president on Tuesday is if a runoff candidate quits unexpectedly and the remaining candidate fails the resulting vote. Needless to say, this is a highly unlikely scenario.

The entire process should take two or three hours. If a runoff is needed, it will be held just 30 minutes after the votes from the first round are tallied.

To ensure that the vote counts are accepted by all sides, the votes will be counted by three MKs, two representatives of the opposition, Labor’s Stav Shaffir and Shas’s Yitzhak Cohen, and one from the coalition, Likud’s Ofir Akunis.