To clear salary-cap space and lock up their franchise quarterback, the Dallas Cowboys and Tony Romo reached an agreement on a blockbuster 6-year extension worth $108 million, making him the highest-paid player in franchise history, according to league sources.

Cowboys chief operating officer Stephen Jones and one of Romo's agents, CAA's R.J. Gonser, spent recent days negotiating a deal that contains more guaranteed money than the six-year, $120.6 million contract that Joe Flacco recently signed with Baltimore, sources said.

Negotiations heated up this week, when the Cowboys submitted their first proposal before Romo's side countered with their own. Negotiations continued at a feverish pace once a framework for the deal was established and middle ground was eventually reached.

By negotiating a new deal with Romo now, the Cowboys will lower his salary-cap number and free up money to sign other players such as former Lions linebacker Justin Durant and former Steelers safety Will Allen. The Cowboys have already agreed to a two-year, $4.4 million deal with Durant and also have an agreement with Allen. For this, in part, the Cowboys can thank Romo, who was scheduled to count $16.8 million against the salary cap and will now count a small fraction of that amount.