TWO former rivals for the Scottish Labour leadership are set to cross swords again in the battle to become Holyrood's new Presiding Officer.

Johann Lamont is understood to be almost certain to throw her hat into the ring, while Ken Macintosh, who she defeated for the leadership in 2011, is said to be "very keen" on the job.

Other contenders, with the role likely but not certain to go to a Labour figure for the first time, include Elaine Smith, who served as deputy presiding officer in the last term and is seriously considering putting herself forward. She said: "Having been deputy Presiding Officer for the last session I feel I have the experience and knowledge to carry out the role. However, I am still speaking to colleagues and considering the matter."

Holyrood's Presiding Officer, the equivalent of the speaker in the House of Commons, will be elected in a secret ballot on Thursday. Bruce Crawford, the SNP MSP, was widely seen as the frontrunner but it is thought unlikely the nationalists will allow one of its cohort to stand after Nicola Sturgeon fell short of securing an overall majority meaning every vote will be crucial.

The Presiding Officer is a politically neutral role, meaning whoever is elected must resign their party membership. Iain Gray, another former Labour leader, is thought to have been keen on the role. However, it is understood that he is unlikely to put himself forward as he believes resigning his party membership would let down the activists who campaigned hard to help him pull off an upset by holding off the nationalists in his East Lothian seat.

Murdo Fraser, the Scottish Conservative MSP, is also to put himself forward and has the backing of his party hierarchy. A senior Tory source said: "Murdo would be an experienced and capable candidate who would be respected right across the chamber."

While MSPs put themselves forward as individuals, rather than party representatives, whips do attempt to influence their MSPs over how to vote. Ms Lamont is understood to have the backing of her party leadership.

Ms Lamont is widely respected across party lines, despite leading her party during the divisive referendum campaign when she would regularly square off with Alex Salmond. Despite being former adversaries, Mr Salmond has previously spoken of his admiration for Ms Lamont, saying the former teacher is "worth 10" of her successor, Jim Murphy, who led the party to a near-wipeout at last year's general election.

One Labour source said: "It's up to the Nats. They're going to have to decide whether they want a strong Presiding Officer who will stand up for the parliament, or a Labour patsy."

It is highly unlikely that a Liberal Democrat will enter the frame, as if the party lost a MSP it would lose representation on the parliamentary business bureau. There will not be a Green candidate, with senior party sources saying they would back whoever they believe would be best placed to push through far reaching reform.

There is a growing clamour across party lines for an overhaul of Holyrood, with concern raised in the last session that the SNP exercised an unhealthy amount of influence over committees, with compliant backbenchers putting party interest over their jobs of holding ministers to account and scrutinising legislation. Previous attempts at reform pushed forward by Tricia Marwick, who will step down as Presiding Officer once her successor is elected, were thwarted by SNP-controlled committees. Whoever is elected Presiding Officer will enjoy a significant pay bump, earning around £45,000 extra on top of the standard MSP’s pay of £60,000.

Duncan McNeil, the long-serving former Labour MSP, stood down in March and used his farewell speech to call for candidates for Presiding Officer to put forward manifestos so they could achieve a mandate for reform.

Yesterday, he called for the process to be brought into the open, and expressed disappointment that it appeared the SNP was putting "party before parliament" by discouraging its MSPs from standing. He said: "This is one of the most important jobs in Scottish politics. I would like to see each candidate underlining why they are standing and what they would do to renew and reform the parliament, which is urgently needed. The horse trading has begun, but it's within the confines of parliament and not educating the public about how important this role is."