PARIS (Reuters) - French President Francois Hollande on Friday hit back at accusations by former election frontrunner Francois Fillon that he was orchestrating a plot to scuttle his bid for power, in a race a new poll on Friday showed is wide open.

With 43 percent of voters undecided before the first round of the presidential election on April 23, according to an Odoxa poll, Hollande, of the Socialist Party, accused conservative Fillon of desecrating the position to which he aspired.

“There’s a degree of dignity and responsibility that has to be respected,” Hollande, the first leader in 60 years not to seek re-election, told franceinfo public radio. “I believe Mr Fillon has overstepped the mark.”

His comments followed an overnight TV show in which Fillon said he was a victim of a plot to spread damaging media leaks in which Hollande was directly involved.

Opinion polls show the election, where 11 contenders face off on April 23 before a two-way playoff on May 7, will be won by independent centrist Emmanuel Macron, 39, who did a stint as economy minister for Hollande before quitting last year to set up a his own political movement.

Marine Le Pen, the far-right leader who is tipped to make it to the final round but lose to Macron, was in Moscow. Her aides said Russian President Vladimir Putin had wished her well in the election at a Kremlin meeting.

Fillon, 63, a former prime minister, had looked sure of winning the presidency in the weeks after he won the candidate-selection contest of his The Republicans party last November.

But he has fallen to third place - meaning he faces first-round elimination - since media revelations in late January prompted magistrates to open an inquiry into allegations that he paid his wife and children hundreds of thousands of euros of public money for minimal work as parliamentary assistants.

In the latest legal twist, Marc Joulaud, who took Fillon’s parliamentary seat when he became prime minister in 2007, was placed under formal investigation on Friday, a source close to the matter said. He had hired Fillon’s wife between 2002-2007 as a parliamentary assistant.

The Odoxa poll suggested the poll rankings of the favorites were fragile, above all for Macron.

The poll said 60 percent of Le Pen’s potential voters and 57 percent of Fillon’s had definitely decided on their candidate. That figure fell to 47 percent for Macron, 44 percent for far-left candidate Jean-Luc Melenchon and 40 percent for Socialist Benoit Hamon.

Investors have been jittery about the possibility of Le Pen, leader of the anti-European Union, anti-immigration National Front, winning the election and taking France out of the euro.

‘GOVERNMENT PLOT’

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Fillon on Thursday blamed Hollande for what he said was a Socialist government plot to kill his candidacy by leaking damaging information to the media.

“Who gives them (media) these documents? The state services,” Fillon said in the interview with France 2 TV.

He stands accused of paying lavish amounts of money to his wife and two of his children, failing to declare a loan from a billionaire and accepting two suits worth 13,000 euros from a lawyer who has a reputation as an intermediary in affairs of state in France and former colonies in Africa.

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When asked if he meant politicians were behind the reports, Fillon said: “I will go much further. I blame the president of the republic.”

Hamon, who served as a minister under Hollande, but has been critical of his former boss, dismissed the accusations.

“We can blame Francois Hollande for a lot of things - and I have on some of his economic policy choices - but if there is one thing I don’t think he is capable of, because it doesn’t correspond with the way he does things, then it’s creating a dirty tricks cabinet,” Hamon told BFM TV.

With Le Pen also being pursued by the French judiciary over use of European Parliament funds to pay staff, Macron, who says he will transcend the Left-Right political divide in favor of cross-partisan government, has risen to the front in the polls.

French Defence Minister Jean-Yves Le Drian, the most popular Socialist government minister after close to 40 years in politics, offered another fillip on Thursday when he said he would back Macron rather than the official Socialist candidate Hamon.

Hamon’s poll ratings make his elimination in round one a near certainty. He called Le Drian’s action disloyal, but the respected veteran said his motivation was keeping Le Pen from power.

As for the future of his party, the 69-year-old told CNews television: “I don’t believe the Socialist Party is dead, I believe it has a future, but it needs to clarify what it stands for ... and become more attractive.”