Section 6. The office of the chief justice for administration and management of the trial court, as provided in section one, shall not be deemed a judicial office as comprehended under the provisions of Article I of Chapter III of Part the Second of the Constitution. Said office of chief justice for administration and management shall be filled by appointment, from among the justices of the trial court departments, by a majority of the justices of the supreme judicial court. The chief justice for administration and management shall hold said office for a term of five years, and shall be eligible to be reappointed for additional five-year terms. The chief justice for administration and management shall be removed by a majority of the justices of the supreme judicial court only for cause in the nature of malfeasance, misfeasance or nonfeasance. The chief justice for administration and management shall retain his commission as associate justice of the trial court, or of a predecessor court to which he was appointed, while serving as chief justice for administration and management, and may continue to perform such judicial duties as he may have exercised as associate justice, and such other responsibilities as otherwise provided by law.