A plan by Prime Minister Vladimir Putin's campaign team to persuade all five presidential hopefuls to sign a "social contract" guaranteeing the fairness and legitimacy of the March 4 election looked in tatters Monday when the last remaining candidate walked out of talks.

Sergei Mironov, of the Just Russia party, said he would sign such a contract only if it is approved by the League of Voters coalition, which was formed during protests over the outcome of December's State Duma elections, Interfax reported.

The initiative was dogged by scandal after TV host Leonid Parfyonov, a leader of the League of Voters, denied that he had approved the document, which was put forward by Putin's camp during a TV talk show episode.

Parfyonov initially supported the idea by Emergency Situations Minister Sergei Shoigu, who stood in for Putin during a recording of the "Citizen Gordon" show on Channel One last week.

But Parfyonov subsequently refused to sign the text, apparently written by pro-Kremlin political analyst Sergei Kurginyan, who also took part in the show.

In the wake of this, the other candidates — billionaire Mikhail Prokhorov, nationalist Vladimir Zhirinovsky and Communist leader Gennady Zyuganov — also said they would not sign.

In addition, the scandal raised eyebrows because Parfyonov's refusal was published in Kommersant on Saturday, more than a day before the airing of the show. All candidates except Zyuganov participated in the program and agreed to support the initiative.

The show was tarnished by the antics of Zhirinovsky, who boisterously walked out of the studio, angrily complaining that vote-rigging would continue.