With the lockout of its musicians now in its fourth week, the Atlanta Symphony Orchestra made a surprise announcement Monday afternoon that its 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 a statement released by the orchestra administration.

The lockout is the second in two years of ASO musicians, and much of their aggrievement during tense collective bargaining agreement negotiations in 2012 — and over eight months of unsuccessful talks this year — has been tied up in their dealings with Romanstein.

His boss, Woodruff Arts Center president and CEO Virginia Hepner, said Monday that she didn’t think that the ASO’s leader for the last four and a half years had been an impediment. “I think it’s a very challenging situation, and he felt like his withdrawal would help,” she said.

Hepner said Romanstein offered his resignation to ASO board chairwoman Karole Lloyd and that Lloyd accepted it.

The Woodruff leader added that Romanstein’s departure does not change the ASO’s financial challenges nor signal any shift in central issues between the two sides.

The musicians, who are scheduled to lose their Woodruff insurance on Wednesday, said in a statement that they “hope this decision will lead to an agreement and end the lockout.” They also encouraged the ASO board to seek “a proven and experienced symphonic arts leader with an outstanding record of fund-raising, marketing and innovation.”

The executive committee of the ASO board moved quickly to appoint Terry Neal, a retired Coca-Cola Company executive and current ASO board member, to serve as 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 announcement said, with Romanstein available to the organization through the end of October “to assure a smooth transition.”

Things have hardly 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.

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 deficits, Romanstein was pushing a proposal in which management, in consultation with music director Robert Spano and musician leaders, would gain control the number of players.

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

Leaders of the ASO Players’ Association charged that Romanstein broke a promise he made to them then to not seek additional concessions this year and were unwilling to trust him with ultimate power over how or when or if open positions would be filled.

Just last week, Spano said that any further reduction to 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 referendum on the future of the ASO itself, questioning in statements issued several times weekly the stewardship of orchestra and Woodruff leaders.

It galled the musicians that Romanstein was listed as having received a $45,000 bonus in the Woodruff’s tax return for 2012, the year of the first lockout, as part of compensation totaling $394,000.

Romanstein, who earned a doctorate in musicology and professed side ambitions to be a choral conductor, embraced his orchestral industry-outsider status when he arrived after serving as CEO of the Minnesota Humanities Center in St. Paul. There he managed a budget of $4.2 million — a fraction of the ASO’s.

“What’s needed are new ideas and new perspectives, ” he told The Atlanta Journal-Constitution shortly after winning the job in 2010. “The [orchestral] business has tended to replicate its mistakes. I don’t come with preconceived notions of the industry.”

Under his watch, the ASO launched a series of one-hour, discounted First Fridays concerts aimed at younger music lovers curious about classical music and cranked up the number of ASO Presents rock and pop concerts in Symphony Hall sans the orchestra.

The orchestra finished the 2014 fiscal year with a $2 million operating deficit on a budget of $37 million, an improvement over 2012, when it had $5 million in red ink.

Romanstein announced last week that all concerts through Nov. 8 had been cancelled. On what would have been the opening night of the ASO’s 70th anniversary season, musicians and several hundred supporters staged a demonstration that they dubbed “A Deafening Silence” outside the Woodruff Arts Center that commanded extensive media coverage.

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 they had expressed interest only in talking with Beck about the process, but had not heard from her and had not yet agreed to her participation.

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