With the lockout of its musicians now in its fourth week, the Atlanta Symphony Orchestra announced Monday afternoon that ASO president and CEO Stanley Romanstein has resigned.

“I believe that my continued leadership of the ASO would be an impediment to our reaching a new labor agreement with the ASO’s musicians,” Romanstein said in an ASO statement.

The lockout is the second in two years of ASO musicians, and much of their frustration during tense collective bargaining agreement negotiations in 2012 and now has been aimed at Romanstein.

Following Romanstein’s surprise resignation, the executive committee of the ASO board appointed Terry Neal, a retired Coca-Cola Company executive and current ASO Board member, to serve as ASO president on an interim basis.

Neal will manage the day-to-day operations of the orchestra until a permanent replacement can be found, the ASO statement said, with Romanstein available to the organization through the end of October “to assure a smooth transition.”

Things have not been smooth for leadership of the ASO and its nonprofit parent group, the Woodruff Arts Center, since the lockout went into effect on Sept. 6 when the two sides could not reach agreement on a new contract.

Pay and benefits are significant issues once again, but an even bigger one this time is the size of the orchestra.

Seeking a sustainable operating model for an organization that has ended 12 consecutive years with a deficit, Romanstein was pushing a proposal in which management would control the number of musicians (or, to employ the industry phrase, “the complement”) going forward.

In the 2012 lockout, the ranks of full-time ASO musicians were trimmed from 95 to 88, with the musicians also grudgingly agreeing to an average pay cut of 14 percent.

Leaders of the Atlanta Symphony Orchestra Players’ Association charged that Romanstein broke promise to them then to not seek additional concessions this time and were not willing to trust him with ultimate power over how open musician positions would be filled.

Just last week, music director Robert Spano said that any further reduction in the complement would require the ASO to lean harder on part-time players at the expense of its sound.

The musicians have turned the issue of the orchestra’s size into a forum on the future of the orchestra itself, questioning in multiple official statements the stewardship of the ASO by orchestra and Woodruff leaders in general and Romanstein in particular.

Romanstein, who was hired in 2010, came from the Minnesota Humanities Center in St. Paul, where he served as CEO with a budget of $4.2 million — a fraction of the ASO’s. He replaced Allison Vulgamore, who had departed after 16 years of growth and controversy.

Karole Lloyd, chairwoman of the ASO board of directors said in the statement announcing Romanstein’s departure: “We appreciate the passion he has brought to advancing the mission of the ASO.”

Virginia Hepner, president and CEO of the Woodruff Arts Center, said in the statement that Romanstein’s resignation does not change the ASO’s financial challenges, “nor signal any shift in the key issues being addressed in the collective bargaining agreement process.”

Last week, Romanstein announced that all concerts through Nov. 8 had been cancelled.

The musicians and ASO and Woodruff leaders have not met since the lockout began.

On Saturday, the ASO announced that the administration and musicians had agreed to resume collective bargaining agreement discussions using federal mediator Allison Beck, credited with helping the Metropolitan Opera bring thorny negotiations to a successful close this summer. That was followed a few hours later by a statement from the Players’ Association saying said they had expressed interest in talking with Beck last Monday, to generally discuss questions about the mediation process, but had not heard from her and had not yet decided to participate.

It was but the latest example of fractured communication between the two sides.

Interim president Neal was elected to the ASO board in 2013 and has represented the ASO on Woodruff Arts Center-wide development initiatives.

He retired from The Coca-Cola Company in 2009 after 30 years, most recently serving as vice president of the Latin America Group and director of Customer Development.