ESPN 730 radio in Charlotte had earlier reported that a deal between Newton and the Panthers was close.
The station, co-operated by former Panthers general manager Marty Hurney, reported that the deal could be done as early as Monday and is likely to run through 2020.
Newton, the first pick of the 2011 draft, is in the final year of his rookie contract. Carolina exercised the fifth-year option on that deal last year, meaning Newton is currently set to make $14,666,666 in 2015 before an extension.
The radio station reported that Newton's new deal, based on the current market, is likely to be worth between $20 million and $21 million a year.
Newton's representatives have been seeking a contract with a high percentage of the money guaranteed and not tied to injuries or other clauses to increase the base value, such as deals the San Francisco 49ers' Colin Kaepernick and Cincinnati Bengals' Andy Dalton signed last year.
Miami Dolphins quarterback Ryan Tannehill, who was picked eighth overall in 2012, recently got a four-year extension worth $77 million in new money with $21.5 million guaranteed. Newton, as the first overall pick in 2011 and a two-time Pro Bowler, is seeking 40-50 percent of his new deal guaranteed.
Newton's overall record is 30-31-1, 1-2 in the playoffs. His 33 rushing touchdowns are the most by any quarterback in his first four seasons, according to the Elias Sports Bureau.
Newton's representatives could not be reached for immediate comment.
Panthers coach Ron Rivera said Tuesday: "No news. We're right where it was yesterday. Right where we left it yesterday."
ESPN NFL Insider Adam Schefter contributed to this report.