According to USPTO spokesperson Jennifer Rankin Byrne, Peterlin's decision to step down early was driven largely by her desire to ensure a smooth changeover, since she is due to have her first child soon and would have been on maternity leave in January.

Doll has been with the USPTO for more than 34 years and has served as a patent examiner, supervisory patent examiner and technology centre director.

Focarino has been with the Office for more than 31 years and also served as a patent examiner, supervisory patent examiner and technology centre director.

There has been much speculation since the election of Barack Obama to the US presidency as to who will be appointed as the new PTO head.

Potential candidates include former PTO director Q Todd Dickinson (1999-2001), who was recently hired as the new executive director of the American Intellectual Property Law Association. Sources indicate that Dickinson "would be open" to accepting the position.

Other possible Obama appointees could include Robert Stoll, director, Office of Enforcement at the USPTO, Steve Kunin of Oblon Spivak Maier & Neustadt, who once served as deputy commissioner for patent examination policy with the USPTO, James Pooley of Morrison & Foerster and Shanna Winters, chief counsel to the subcommittee on the courts, internet and intellectual property.

In a statement released Friday, USPTO director Jon Dudas said: "With John's and Peggy's leadership, we will ensure that the important work of the Deputy Under Secretary and Deputy Director, as well as that of the Commissioner for Patents, continues in an uninterrupted fashion, which is good for our employees, the agency and the intellectual property system."

It is unclear how long the interim team will remain on, as that depends on how long it takes for a new director to be appointed. Rankin Byrne said that in the past it has taken up to 10 months after an administration change to appoint a new USPTO director.