The former South Australian premier Jay Weatherill has endorsed the Labor left frontbencher Mark Butler to remain as ALP national president, underscoring his longstanding commitment to party democratisation.

The fresh endorsement surfaced just before the close of nominations for the ALP national president on Friday. Butler, currently party president, is trying to secure a second term against significant pushback from the right faction.

Also in the field is the Queensland rightwinger Wayne Swan, the former treasurer and deputy prime minister during the Rudd/Gillard period, who is making a concerted pitch for left votes by highlighting his front-running policy advocacy on inequality during this period in opposition.

Another leftwinger, the Queensland senator Claire Moore, is expected to nominate and there are suggestions a fourth candidate connected with the right faction may yet emerge.

Once nominations close, ALP members will elect three positions: party president, vice president and junior vice president.

Weatherill has recorded a video endorsing Butler – his South Australian colleague and longtime friend – trumpeting the frontbencher’s advocacy on climate change and renewable energy, and his commitment to increasing grassroots participation in party votes and forums.

The former South Australian premier says in the video Butler is committed to increasing party democratisation, including allowing rank-and-file voting for Senate preselections – which is a controversial push institutionally.

Both Butler and Swan are currently travelling the country in an effort to court voters.

Swan launched his campaign in Sydney on Tuesday night and Butler has fronted events in Sydney and Melbourne over the past few days. Swan will spend the next couple of days in Melbourne and in Tasmania.

Swan’s campaign is emphasising the fact he will have time to devote to the role, given his recent confirmation that he won’t stand again for parliament at the next federal election; and his advocacy on economic issues.

Left candidates generally prevail in grassroots votes, reflecting the dominance of left-aligned party members in the party’s big inner-city branches, but the right has endorsed Swan to run believing he will attract cross-factional support because of his relentless campaign to make the ALP’s economic policy offering more progressive.

Butler’s push for democratisation has seriously alarmed the right faction, which generally resists proposals to open up party processes on the basis it increases the power of the left in internal forums.