The Red Sox will pay $9 million of Lowell's $12 million salary. The trade was first reported by FoxSports.com.
A cash transfer of that magnitude would require approval from the commissioner's office. The Rangers, with cash-strapped owner Tom Hicks selling the team, are essentially having their every financial transaction scrutinized by MLB, so the deal needs commissioner Bud Selig's approval, not only because more than $1 million will change hands but also because the Rangers will be picking up an additional $3 million in salary.
The commissioner's office had not been asked to approve the deal as of late Thursday night, according to a source. Another source said Selig, with some reservations, will grant his approval, unless there are some other issues that have yet to be disclosed.
Rangers GM Jon Daniels had said Thursday morning that both teams still had the option of walking away from the deal, but other club executives said it was their understanding that the deal would move forward. One team that looked at Lowell was Houston, whose new manager is former Red Sox bench coach Brad Mills, but the Astros decided that he was too great a question mark to play third base, according to one source. The Astros are close to a one-year deal with free-agent third baseman Pedro Feliz, sources told ESPN.com.
Red Sox GM Theo Epstein left the winter meetings before the Rule 5 draft and has not responded to requests for comment.
Passing a medical exam may not be the formality it is in many trades. Lowell, who turns 36 on Feb. 24, underwent surgery after the 2008 season for a torn labrum in his right hip, which drastically affected his mobility in the field last season. Lowell played in 119 games but missed a dozen games when he went on the disabled list because of a strained hip.
Lowell also missed nearly a month at the start of the 2008 season with what was called a sprained left thumb.
Asked if the remaining hurdles to the deal were health or financial issues, Daniels said, "Any of the above. Both clubs have the ability to pursue other options."
Asked about the financial portion of the deal, Daniels said, "The general parameters are understood and both clubs need to decide whether it's the right fit.
"There's a financial component to it, but I'm not going to address that specifically. Both clubs know what's on the table and we'll continue to talk and work through it," he said.
But an official of another club that had been talking with the Red Sox about Lowell said Thursday that it was his understanding that an agreement had indeed been reached.
Lowell, who attended David Ortiz's charity golf tournament in the Dominican Republic last weekend, said at the time that he had not "missed a single moment of sleep" because of rumors that the Red Sox -- uncertain that he would make a full recovery -- were planning to trade him. Lowell, who reiterated that doctors had told him he would require a year to heal, said he felt much better than he had last season.
The Rangers, if the deal goes through, would use Lowell as a right-handed designated hitter and part-time first baseman, a position he has never played in the big leagues. Lowell has played 1,470 games at third base, winning the Gold Glove in 2005.
Red Sox manager Terry Francona, asked last week about flipping Lowell to first and returning Kevin Youkilis to third, rejected that idea.
"I'm not for it," Francona said. "The guy has played third base his whole life. He could do it, but I don't know if it's as easy as people think, and I don't know if it's in his best interests."
Francona said moving Lowell to first base could actually increase the stress on his surgically repaired right hip, since it would introduce a whole different set of movements at a new position.
Ramirez, a 25-year-old native of Venezuela, was originally signed by the Braves and has played parts of the last two seasons with the Rangers. He is considered a better hitter than catcher.
Gordon Edes is ESPNBoston.com's Red Sox reporter. He has covered the Red Sox for 12 years and has reported on baseball for 25 years. Information from ESPN The Magazine's Buster Olney and ESPNDallas.com's Richard Durrett was used in this report.