The Senegal striker only left Tyneside in January, joining Chelsea on a three-year deal after they activated a £7m release clause in his contract.
Ba has made just the one appearance in the Premier League this season in the 2-1 win against Aston Villa.
With Romelu Lukaku's return from his loan spell at West Brom, Ba has come under pressure at Stamford Bridge, although he insisted in July that the extra competition would make him "play better".
Last season, the 28-year-old scored six goals in 22 games as the club secured a third-place finish in the Premier League.
Newcastle are also understood to have re-opened talks with Lyon over the potential signing of France striker Bafetimbi Gomis.
The Magpies have brought in Loic Remy on loan from QPR already this summer but he remains their only summer recruit to date.
Alan Pardew has been more concerned with keeping his squad intact, with Arsenal's pursuit of midfielder Yohan Cabaye occupying his time.
The Toon boss is set to address transfers later on Wednesday when he faces the media after the Capital One Cup second-round tie at Morecambe.