BATTLE lines have been drawn ahead of what is set to become an explosive power struggle over the identity of Holyrood's next Presiding Officer.

With the SNP expected to retain control of the parliament, Labour said that no party with a majority should put forward one of its MSPs for the crucial role.

Labour claimed the move would help the Scottish Parliament return to its 'democratic, pluralist principles'. It follows claims that the SNP wielded an unhealthy amount of power over the last term, when its backbenchers were accused of putting loyalty to party bosses ahead of responsibilities to hold the executive to account.

The nationalists hit back at the demand, saying it should not be for any party, far less one polling barely a fifth of the vote, to attempt to dictate parliamentary process to others.

The Presiding Officer, the equivalent of the Speaker of the House of Commons, resigns their party membership and becomes neutral after being elected by fellow MSPs and chair proceedings in the chamber as well as the Scottish Parliamentary Corporate Body and the Parliamentary Bureau. They are elected in what is Holyrood's only secret ballot, with candidates becoming eligible when nominees receive the backing of one fellow MSP rather than their party. However, it is suspected that party whips still exercise substantial control over the process.

There has never been a Labour Presiding Officer. While Johann Lamont is mooted as a potential candidate by some at Holyrood, there are doubts over whether SNP members would vote for a former opposition party leader ahead of one of their own.

Potential candidates from the SNP's ranks include Bruce Crawford, the former minister for parliamentary business, who is widely respected by MSPs of all parties.

The last presiding officer, Tricia Marwick, was elected as an SNP MSP before being chosen for the role five years ago. Her attempts at reforming the Scottish Parliament were thwarted by an SNP-controlled committee after she called for convenors to be elected by peers rather than party bosses.

While Holyrood's committee system was originally seen as a strong point of the fledgling parliament, an unexpected majority for the SNP meant it held more than half of the positions on almost all of the 18 bodies, which are tasked with holding the government to account as well as scrutinising and amending legislation.

Opposition parties accused the Nationalists of using their voting power to block potentially embarrassing inquiries and water down reports critical of government policy, going as far as to call an extraordinary press conference in 2014 when they claimed SNP MSPs were blocking the publication of criticism of Alex Salmond’s government.

In a manifesto commitment, Labour said: "We need a return to the democratic, pluralist principles of the early parliament. Scrutiny of government is critical to making good laws and ensuring democracy is transparent. If a party has a majority in parliament, then that party should not also hold the majority of committee convenorships and should not nominate a member for the position of Presiding Officer. We will bring these proposals to parliament when it returns."

A new presiding officer will be elected on May 12, a week after the Holyrood election. While the position is sought after, there is the possibility that Labour or Tory MSPs may be discouraged from standing if the parties end up tied on seats meaning losing an MSP would leave them as the third party at Holyrood.

A spokesman for the SNP said: "The election of a Presiding Officer is a matter for the Scottish Parliament as a whole, and based on an open vote among all MSPs. It is not for any party - far less one currently polling barely a fifth of the vote - to try and dictate how these things should be decided."

He added: "Labour’s problem isn’t the way parliament is run - it’s that Labour have let down Scotland’s voters by siding with the Tories."

Willie Rennie, the Liberal Democrat leader, said that Holyrood needed to be "rigorous and robust" in scrutinising legislation but claimed SNP backbenchers had been "timid and afraid" to speak out against their party bosses.

Patrick Harvie, the Green co-convenor, backed Holyrood reform to ensure there is robust scrutiny of the new powers being devolved, but said it should take place regardless of whether a party wins a majority.

He added: "It goes way beyond the question of who is elected as Presiding Officer - a more open, participative Holyrood would add to the scrutiny capacity, and would ensure that decisions aren't made in a closed political bubble."