The man who once said, "If someone tells you he has a new interpretation of Islam, sock him in the mouth" is now one of the most powerful men in Iran.

Ayatollah Mesbah Yazdi, an ultra-conservative hard-liner, has been elected chairman of the powerful clerical body the Assembly of Experts.  The assembly elects – or removes – the supreme leader and guides him in his decisions on whether a law meets sharia requirements.

Ayatollah Mohammad Yazdi, 83, was a deputy speaker of parliament after the 1979 Islamic revolution and headed the judiciary for a decade until 1999.

He gained 47 of the 73 votes cast at a closed-door meeting in Tehran, according to the website of state television, citing officials.

Yazdi was among five contenders whose names had been linked to the post by Iranian media in recent weeks but he was not the most talked about.

His election represents a heavy defeat for former president Akbar Hashemi Rafsanjani, a relative moderate who previously held the position between 2007 and 2011, and who received 24 votes.

Yazdi, described in Iran's official Who's Who as rightwing, takes up a position vacant since October 2014, when Ayatollah Mohammad Reza Mahdavi Kani died following a heart attack.

    Officially comprised of 86 religious figures elected by the people, the Assembly of Experts chooses the supreme leader and monitors his actions.

The clerical body grants the leader, currently Ayatollah Ali Khamenei, an indefinite term but it retains the power to sack him, if it sees fit.

Yazdi, initially at least, will hold the post for just one year as elections for the Assembly of Experts are scheduled alongside parliamentary polls next year, with a new vote for chairman to follow.

Although Rafsanjani put his name forward, he had appeared reluctant to resume the post, insisting his membership of Iran's top political arbitration body, the Expediency Council, already kept him busy.

As the Jerusalem Post reports, current supreme leader Ayatollah Ali Khamenei is suffering from Stage 4 prostate cancer and probably has less than two years to live.  The significance of Yazdi's election is that he is now in an excellent position to grab the top spot when Khamenei dies.  Yazdi has been mentioned prominently as a successor to Khamenei for more than a decade.  But given his age – 83 – he is likely to be a short-term solution to their leadership problem.

Yazdi served as head of the judiciary branch of government for many years and is a member of the Guardian Council.  He was designated to lead Friday prayers in Tehran – a position that required him to lead the "Death to America" chant after every Friday service.

The new head of the Assembly of Experts is also a "twelver" – a believer in the apocalyptic vision of the return of the 12^th Imam, who will bring about a world caliphate under sharia law.

Yazdi is one of the last of the Old Guard Islamic clerics who seized power in 1979.  He studied under Ayatollah Khomeini and was at his side during ther revolution.  The "younger" generation of ayatollahs (in their 50s and 60s) are about to move into positions of leadership in the regime.  They are no less anti-American or anti-Western than their elders.  And they wouldn't dream of easing restrictions set up by sharia law.  In short, anyone hoping for significant change in Iran once the Old Guard passes on is fooling himself.