Towers said he, CEO Sandy Alderson and Black will meet Friday to discuss the vacancies before moving ahead toward a decision next week.
Lefebvre, 66, has been a Minor League hitting consultant with the Padres since 2006 and, most recently, served as the manager of the Chinese national team since it was formed in 2003. He managed the team in the World Baseball Classic in 2006 and the Beijing Olympics in August.
Lefebvre, who has a 417-442 record as a Major League manager with the Mariners, the Brewers and the Cubs, previously has been a hitting coach with the Giants, A's, Brewers and Reds.
Simmons, 59, served most of this past season as the bench coach in Milwaukee as part of manager Ned Yost's staff. When Yost was fired on Sept. 15, Simmons was re-assigned to an advisory role with the team.
The Padres have been granted permission by Brewers general manager Doug Melvin to talk to Simmons, though Towers might need to seek additional approval from the league office or wait until his contract expires at the end of October.
Simmons is no stranger to the Padres organization. He served as a Major League scout for the organization from 1999-2007. After a 21-year playing career, Simmons headed the Cardinals' Minor League system, was the general manager in Pittsburgh briefly before working in the front office in Cleveland and then San Diego.
Padres hitting coach Wally Joyner resigned during the final week of the regular season, citing a difference in approach to hitting to that of the organization. Bench coach Craig Colbert was let go a day after the regular season ended.
Also on Wednesday, the Padres outrighted infielder Craig Stansberry and pitchers Kevin Cameron and Tim Stauffer to Triple-A Portland, freeing up more room on the 40-man roster. The 40-man roster now is at 32.
Corey Brock is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.