Gilbert, now a special adviser for the Chicago White Sox, and his advisers met Wednesday with officials from the Rangers and Hicks Sports Group and toured Rangers Ballpark.
Pittsburgh attorney Chuck Greenberg and Houston businessman Jim Crane, the other potential owners, had meetings last week.
It is unclear if there are more potential investors, or if Gilbert, Greenberg and Crane are the only candidates. A Hicks Sports Group spokeswoman didn't respond to an e-mail seeking clarification. The company's release said there would be no further comment on the process.
Financially strapped owner Tom Hicks said this summer that he was willing to sell controlling interest in the Rangers. He has since indicated that he would like to still be in some position of ownership when the process is completed.
Hicks also owns the NHL's Dallas Stars through Hicks Sports Group and separately co-owns Liverpool of England's Premier League with George Gillett Jr.
Hicks and Gillett have been seeking investors but say they want to keep controlling interest of the soccer team. Liverpool officials said last weekend that the team will have new investors within six months, broadening ownership that will include Hicks and Gillett.
Gilbert is a former minor league player who became successful in insurance, writing policies for some entertainers in California and athletes. He later became an agent, and his clients included George Brett, Barry Bonds, Bobby Bonilla, Mike Piazza and Curt Schilling.