Political tensions are mounting ahead of Monday's Knesset vote on the next state comptroller.

A week ago it appeared that the decision had been made: A broad coalition of MKs, mostly from Likud, Kadima and Yisrael Beiteinu, supported the appointment of District Court Judge Yosef Shapira. But that was before Justice Eliezer Rivlin, vice president of the Supreme Court, decided to run against Shapira.

In a surprising development, Rivlin's candidacy is now enjoying substantial support from both coalition and opposition parties. Shapira might be unable to rally an absolute majority in the Knesset in the first round of voting, on Monday. Shapira is still the leading candidate, but he is no longer a shoe-in.

The differences between Rivlin and Shapira are enormous. Rivlin has logged 36 years experience on the bench, 13 of them on the Supreme Court, and has a proven record of integrity and reasoned rulings. Shapira is a good, but relatively junior, judge. His main advantage over Rivlin is that he happens to be the personal attorney of Prime Minister Benjamin Netanyahu, former Netanyahu legal adviser David Shimron and Kadima MK Roni Bar-On. It is his network of connections in the capital that has made him a leading candidate for the state comptroller slot.

Over the past several months unease has grown over Shapira's possible appointment in the political, judicial and civil service establishments. Many individuals raised concerns that his appointment would weaken the institution of the state comptroller so much as to render it impotent.

Rivlin's decision to join the race, at this relatively late stage, appears to stem from these concerns. This also explains the last-minute support voiced by dozens of MKs from across the political spectrum for Rivlin's candidacy.

A total of 64 MKs have declared their support for Shapira so far. His candidacy was put forth by MKs Yariv Levin (Likud ) and Dalia Itzik (Kadima ) and was supported by Netanyahu and then-Kadima chairwoman and MK Tzipi Livni.

Rivlin's candidacy had been discussed earlier by Labor. Eleven MKs have expressed support for Rivlin, although many believed he would not enter the contest because of the massive support for Shapira.

A third candidate - the president of the Institute of Internal Auditors, Shlomo Kalderon - is not considered to be a genuine contender.

After Mofaz was voted chairman of Kadima in the party primary earlier this year, some observers suggested he might want to differentiate himself from Livni and support Rivlin. That issue was rendered mute by his joining of the coalition last week.

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