"The longer the chip crisis lasts, the harder it will be to sustain the auto industry's current business model," Stellantis boss Carlos Tavares told a FT web conference.
Barra added that the No. 1 US automaker's "supply chain and manufacturing teams are maximizing production of high-demand and capacity-constrained vehicles."
In a conference call with reporters, Barra said that the chip shortage will worsen in the second quarter before starting to improve in the second half of the year.
Ferdinando Uliano said FIM CISL was asking the company to meet its target to start (Tonale's) production by the end of this year.
"We want to be on the market with the most updated electrified offer, leveraging on the Stellantis technology and know-how. Our teams in Pomigliano are strongly working to update the production line," it said.
As part of its plan, Stellantis has said it would increase the number of hybrid or fully electric vehicles to 40 models by the end of this year from 29 now.
Stellantis plans to have fully-electric or hybrid versions of all of its vehicles available in Europe by 2025, broadly in line with plans rivals such as Volkswagen and Renault-Nissan.
Production at the plant, where the world's fourth largest automaker makes Jeep Renegade and Compass models and the Fiat 500X compact SUV, has been repeatedly disrupted due to weak demand and semiconductor supply shortages.
The FIM CISL union said last week the firm was considering permanently closing one of its two production lines at the Melfi plant to address excess capacity in Italy.
Jeep's Renegade and Compass models and the Fiat 500X compact SUV are produced at Melfi, which is considered the most efficient Stellantis plant in Italy, but could be moved to a single production line.
The carmaker's production is under scrutiny in the country for costing more than elsewhere, as Stellantis seeks more than 5 billion euros ($5.9 billion) a year in savings.
Ford said it will idle its Ohio assembly plant, while its Kentucky Truck Plant in Louisville will only work two of three shifts. Both plants will return to full production the week of March 29.
The US automaker said the latest action is part of a prior forecast it made that the shortage could hit 2021 profits by $1 bln to $2.5 bln.