The deal is for $26 million guaranteed with incentives that could push the deal to $30 million. The contract is expected to be announced soon, pending a physical.
As a precautionary measure, Boston made a qualifying offer of $13.3 million to Ortiz on Friday, guaranteeing the club will receive Draft compensation if the slugger signs with another team.
"Well, we're working on it," said general manager Ben Cherington on WEEI's Hot Stove program on Thursday night. "We've been talking to David since the end of the season, and it's been a good conversation. Everyone knows that we'd like to keep him, and I think there's mutual interest. And we've had a lot of talks, and we've made up some ground in some areas, but we still have some work to do."
The Red Sox didn't make qualifying offers to any of their other six-year free agents, a group that includes Cody Ross, Daisuke Matsuzaka, James Loney, Vicente Padilla and Scot Podsednik.
While Ortiz has played on one-year contracts the past two seasons, the sides have been trying to hammer out a multi-year deal.
"We'll keep working on it," Cherington said. "If we get past tomorrow night, we'll continue to work on it. We remain hopeful that we'll keep him in a Red Sox uniform next year."
Last year, Ortiz accepted Boston's offer of arbitration and nearly went to a hearing before the sides agreed to a one-year deal in February.
Things should happen at a much swifter pace this year, thanks to the new rules in the Collective Bargaining Agreement.
Under the new system, six-year free agents aren't eligible for arbitration. Ortiz has until 5 p.m. on Wednesday to accept the qualifying offer. If he declines, the sides can continue to try to work out a deal.
"Well, the landscape has changed a little bit in terms of the rules," Cherington said. "Arbitration process and rules for a free agent like David are different than they were last year. The one thing we know for sure is we won't be going through a traditional arbitration process. It won't be drawn out like it was last winter and potentially even getting close to a hearing, as we did last winter.
"I think obviously we would all like to avoid that, and we know that won't happen this year, so that's different. Aside from that, it's just, we have a guy who's been here for a long time who's been a really important part of the team and a guy we want to keep and it's just a matter of trying to find a deal that works for him and works for us. We're still working on that and hopefully we can get something done."
Ortiz batted .318 with 23 homers and 60 RBIs in only 90 games in 2012, missing most of the second half with a right Achilles injury. He has batted .290 with 343 homers and 1,088 RBIs in his 10 seasons with Boston.
The other free agent the Red Sox are trying to retain is Ross, who probably will play the market a little before it's determined if a return engagement to Boston is realistic.
A year ago, Ross didn't have a lot of leverage, coming off a down year with the Giants. But he rebounded nicely during his one-year contract with the Red Sox.
"He's in a better position this year than he was last year," Cherington said. "That's good for him. It creates a bigger challenge for us in trying to find a deal that works for him and works for us. We have talked, and talked a lot. Time will tell. If we do get past tomorrow night, certainly he'll have options, and we've got to weigh what it would take to sign him vs. alternatives in the market. That's the process.
One area where the Red Sox have an opening is first base. Is it possible Kevin Youkilis -- now a free agent -- could return to the club to fill that spot?
"On a personal level, certainly nothing happened that ... there was no break in the relationship, I don't think," Cherington said. "He'll have choices, and we'll have choices. We'll just see where the offseason takes us."
Though the free-agent market is light on starting pitching, Cherington mentioned he would like to add an external candidate to a rotation that is likely to include Jon Lester, Clay Buchholz, John Lackey and Felix Doubront.
"We'd like to add to the rotation, whether that's through free agency or trade, we'll explore both options; we'd like to add someone externally to that group you mentioned," Cherington said. "And we'd like to protect, if at all possible, the younger arms in the system who may not be on the team in April of 2013 but who we believe can be part of a really good rotation moving forward."