Just in from the Irish News political correspondent, John Manley
— Irish News Politics (@politicsIN) September 27, 2015
I would imagine some backers of his push will involved Mark Durkan MP and Claire Hanna. Backers of McDonnell will include Fearghal McKinney and Alban Maginess.
Some key folks to watch in terms of who they side with are the former leader Margaret Ritchie, former minister Alex Attwood and Patsy McGlone.
David McCann holds a PhD in North-South relations from University of Ulster. You can follow him on twitter @dmcbfs