Labor Party leader Ehud Barak's 56 percent to 44 percent victory over outgoing Prime Minister Binyamin Netanyahu, signifying the collapse of the "Greater Israel" ideology, is the seismic shift that has brought undisguised joy from leaders around the world.
But the massive success of the fervently Orthodox, or haredi, Shas Party, which draws predominant support from Israel's Sephardi population, is also an earthquake.
Shas scored the most dramatic victory in Monday's voting for the Knesset, boosting its representation from 10 seats in the outgoing Knesset to a projected 17 seats in the new legislature. The gain makes it one of the "Big Three" in the Knesset, alongside the much-reduced Likud and Labor factions.
According to projections, One Israel, the Labor Party coalition, will have 27 seats, compared with Labor's 34 in the outgoing Knesset; Likud will have 19 seats, a loss of 13 from the outgoing Knesset.
Given that Shas' strident election campaign focused almost exclusively on the four-year sentence for bribery and corruption recently imposed on its leader, Aryeh Deri, the party's victory, on the face of it, is a victory for the anti-court and anti-establishment rhetoric that its leaders espoused.
Deri announced Tuesday he was resigning as a Knesset member and withdrawing from political life in a move that could clear the way for coalition negotiations between Barak and Shas.
But on a deeper level, Shas' triumph dramatically illustrates the daunting task facing Barak in his quest, as he proclaimed on election night, for unity, brotherhood and a "healing of the rifts" that have threatened to tear apart Israeli society.
Ironically, it was Netanyahu's close alliance with Shas that, probably more than any other single factor, brought on his crushing defeat. As the election campaign neared its climax -- and especially after Deri's sentencing in April and Shas' vociferous rejection of the ruling -- it became increasingly clear that Netanyahu's "coalition of the nonelites," as opposed to the "elitism" he ascribed to Labor's traditional Ashkenazi following, was splitting at the seams.
The vast immigrant community from the former Soviet Union bridled at finding themselves lumped together in Netanyahu's governing coalition with a convicted felon whose followers were threatening the judges who had found him guilty.
Yisrael Ba'Aliyah, the immigrants' rights party led by Natan Sharansky, brilliantly turned this sentiment to its electoral advantage by running a catchy campaign directed against Shas' control of the Interior Ministry.
Shas officials, Yisrael Ba'Aliyah claimed, used their power in that ministry to harass and discriminate against immigrants whose Jewish status, under religious law, was deemed uncertain or unsatisfactory.
In the month before polling day, tens of thousands of immigrants shifted their support from Netanyahu, viewed as being in thrall to Shas, to Barak, whose election promise was, "I will not bow to extremists."
On the morning after, however, all election promises must undergo searching re-examination under the harsh light of the new Knesset arithmetic.
Shas' 17 "extremists" are not, arguably, as easily dismissed as 10 of the same.
In practical terms, Barak will find it hard to set up a stable government without either Shas or Likud. On paper, it is possible. But the patchwork of agreements with tiny factions that this would entail is a recipe for grief.
Granted, his theoretical ability to do without Likud and Shas will lend him strength in his negotiations with one or both of these factions as he moves forward in forming a coalition government.
Projected Knesset results give Barak several possible allies to choose from in the 45 days he now has to form that government:
* The Meretz Party will have nine seats, the same as in the outgoing Knesset;
* Yisrael Ba'Aliyah is estimated to have won seven seats, also the same as it had in the outgoing Knesset;
* Shinui, a new party that says all fervently Orthodox parties should be kept out of the next government, will have six seats in the new Knesset;
* The Center Party, the new grouping headed by Yitzhak Mordechai, who dropped out of the race for prime minister a day before elections, will have six seats; and
* The National Religious Party will have five seats, compared to nine in the outgoing Knesset.
If the NRP agrees to enter an otherwise secularist and left-of-center coalition, this would give Barak something of the unifying "rainbow effect" for which he has pledged to strive. Nevertheless, his larger goal of reconciliation would seem to dictate a pact with Shas or Likud. Most pundits believe he will try to include one of them in his coalition.
Each, however, holds out major problems for Barak. Meretz, a natural Barak ally, has issued a firm declaration that it would refuse to join any government with Shas. In this, Meretz is following the lead of another election success story, the avowedly anti-Orthodox Shinui Party.
Barak needs one or both of these factions inside his tent. But how can he get them there and have Shas inside, too?
Indeed, within Barak's own party there is a strong body of opinion opposing a deal with Shas. During his victory address at Rabin Square on Monday night, Barak was confronted with placards demanding "Not the haredim" -- and the huge throng picked up that slogan and shouted it at Barak and his leadership team.
But Labor Knesset member Yossi Beilin has left the door open for negotiations with Shas, saying that Labor had ruled out negotiating with Shas only if Deri remained at its head. Barak himself had pledged not to negotiate with Deri since the Shas leader's conviction.
But this obstacle has been removed because Deri, with a historic victory under his belt, has stepped down to prepare his appeal and allow others to run the party for the meantime.
Likud, smarting from its defeat and reeling under Netanyahu's swift resignation, will now undergo a grueling leadership battle.
The political persuasion of the new leader may prove a determining factor in whether Likud is prepared to make the doctrinal compromises necessary for a partnership with Labor.
For their part, Barak and his team are not prepared for a unity government that is in effect a government of paralysis, which was the case for the governments that ruled from 1984 to 1990. His resounding victory in the vote for prime minister gives him the perfect right to insist that any coalition must follow One Israel's lead.
Two likely Likud leadership contenders, Jerusalem Mayor Ehud Olmert and outgoing Finance Minister Meir Sheetrit, are seen as relative pragmatists.
But hardliner Ariel Sharon seems to be preparing a leadership bid as well. This could spell the end of any possible alliance with Barak.