Marshall turns 36 next month and has been holding out hope for one final year in the NRL after being cut loose by the Wests Tigers.
The popular playmaker spent time with Bennett with the New Zealand test team and then again with the Broncos in 2017.
While a deal is yet to be officially struck, there have been positive talks between Marshall and Souths.
Souths’ starting halves Adam Reynolds and Cody Walker are two of the best in the business, but Marshall would be a handy back-up option – and at a cut price – and provide plenty of experience to the Redfern group many have already tipped to win the premiership.
Marshall, who has now played 324 NRL games, remained one of the Tigers’ best players last season, despite being dumped from first grade for a few weeks.
He had a big-money offer on the table from Hull FC where former Tigers teammate Brett Hodgson is now coaching, but was not keen to leave Australia, especially with wife Zoe expecting their second child.
Zoe has spoken in the past about their struggles to conceive a baby. It was the same reason Marshall passed on the chance to link with North Queensland.
Marshall, a Wests Tigers hero, left the club at the end of 2012 to play in Super Rugby with the Auckland Blues, only to return to the NRL with St George Illawarra and then the Broncos before a Tigers homecoming in 2018.