The state-run maker of Malaysian econoboxes bought a controlling share of Lotus in 1996, but 15 years later, the brand has yet to realise a profit.
While the planets are quickly moving into alignment for Lotus - it expects to launch a raft of impressive new models from 2013 - plans for Proton to split off into a private company has investors pushing for a sale.
"It will make sense for them to sell it," investor Gan Eng Peng told Bloomberg this week. "Proton and Lotus are not a good fit. They are in different market segments, both in terms of geography and product."
Reports describe interest in the Lotus brand from China's Shanghai Automotive Industry Corporation and Luxembourg-based Genii Capital, although both companies have denied any plans.
Lotus boss Dany Bahar told Bloomberg that the brand's plans will see it break even in 2014, if the financial backing to continue development of its new models is secured.
"The only thing we can do is show the current owners, or the new owners, that we are absolutely in line with the business plan that we have presented," Bahar said.
"Without the funding support and the guarantees given by the Proton group, we would not survive, end of story."
It is estimated that Lotus will need to sell around 8000 of its current and new models before it will turn a profit. Last year, the brand sold just 1985 cars worldwide.