Labor MK Shelly Yachimovich broke ranks with her party on Monday, announcing her support for Likud MK Reuven Rivlin for president. Yachimovich, who served as the center-left party’s leader until November of last year, is the only Labor MK not to pledge support for the party’s own candidate — veteran MK and former defense minister Binyamin Ben-Eliezer.

Yachimovich called Rivlin a champion of democracy who, as Knesset speaker, strove to uphold the rights of all parties, even those he opposed politically.

“As a right-wing man, whose opinions are in many instances completely opposite to mine, he has withstood the test,” Yachimovich wrote in a post on her Facebook page.

“He is honest and honorable,” she said, “humble in his conduct and genuinely statesmanlike in his thinking and in his behavior.”

“I have followed him for many years, eight of them in close proximity,” Yachimovich wrote. “In the Knesset, in the Finance Committee, as Knesset speaker, through trying situations — and I feel that it is a great privilege to serve with him in parliament.”

Rivlin, she said, “is the most deserving and most suitable to serve as president.”

Yachimovich’s announcement represented a further blow to Ben-Eliezer’s bid, after Yesh Atid head Yair Lapid on Sunday instructed his party colleagues not to cast ballots for the Labor candidate in the closed vote next week as a punishment for the latter’s absence during a March vote on ultra-Orthodox military enlistment.

The president will be picked from among six candidates by the 120 members of the Knesset in a secret ballot set for June 10.

Last week Prime Minister Benjamin Netanyahu also announced that he would back Rivlin in the presidential election. Netanyahu’s endorsement would seem likely to bolster Rivlin’s chances of winning the post for which he is already the favorite, but since MKs vote in secret ballot, surprises are possible.

Netanyahu’s announcement ended a period of hearsay and controversy swirling around the presidential race. Earlier this month, Hebrew media reported that Netanyahu was aiming to postpone the elections for up to six months, during which time he could push through a law abolishing the presidential office, apparently because he wanted to block frontrunner Rivlin. This idea was quickly shot down by Lapid, a key coalition partner. On Monday night, the prime minister was said to have contacted heads of political parties in a bid to back Holocaust survivor Elie Wiesel for president. Wiesel is not an Israeli citizen, and in 2007, when Ehud Olmert was prime minister, rejected a similar offer.

Aside from Rivlin, the candidates are Ben-Eliezer from Labor, Hatnua MK Meir Sheetrit, former Supreme Court justice Dalia Dorner, former Knesset speaker Dalia Itzik, and Nobel laureate in chemistry Daniel Shechtman.

Adiv Sterman contributed to this report.