Peyton Manning deadline looms

The Indianapolis Colts have until Thursday to pick up the remaining four years on Peyton Manning's five-year, $90 million contract, which includes an option bonus of $28 million.

If the Colts release Manning by 4 p.m. ET that day, they owe him nothing.

If they choose not to pick up the option bonus but don't release him by 4 ET, they still would owe Manning the same $28 million bonus for not exercising the option on his contract. That $28 million must be paid by Sunday, two days before the start of the league year on March 13. If the sides agree to a restructured contract by Sunday, the Colts would not have to pay Manning the $28 million non-exercise fee.

Manning has increased his throwing regimen as Colts owner Jim Irsay contemplates a decision on whether to exercise the option. Manning and Irsay also have had conversations about the veteran quarterback continuing his career as a Colt, even though it is likely the team is set to use the No. 1 overall draft pick on former Stanford quarterback Andrew Luck or former Baylor quarterback Robert Griffin III in April.

Several sources have told ESPN during the past month that Manning's throwing strength has dramatically improved as his nerves continue to regenerate following his latest neck surgery Sept. 8. Dr. Robert Watkins, who performed the single-level cervical fusion, has stated publicly that he has cleared Manning to resume his playing career.

ESPN senior NFL analyst Chris Mortensen contributed to this report.