A retiring Liberal senator with more than three years left on his term has been announced as Australia’s next consul-general in Chicago.

News of the appointment came just an hour after David Bushby, the chief government whip in the Senate, announced he would retire from the Senate on Monday.

Bushby’s decision to vacate his Tasmanian Senate seat early will create a casual vacancy for the Liberal party to fill until June 2022, when his term was due to end.

While generous tributes flowed in from his Liberal colleagues, political opponents questioned the merit of his appointment to the consul-general post.

Former independent MP Rob Oakeshott – who announced on Tuesday that he would recontest the seat of Cowper – said the appointment was “the sort of stuff that is making people angry” about politics.

This is the sort of stuff that is making people angry. https://t.co/8SkVLhSenm — Rob Oakeshott (@RobOakeshott1) January 18, 2019

The Coalition has a strong record of finding government jobs for its former Tasmanian members, appointing Andrew Nikolic to the administrative appeals tribunal, Eric Hutchinson as the administrator of Norfolk Island and Brett Whiteley to an advisory role in Malcolm Turnbull’s office.

In a statement, Bushby said it had been “an honour and a privilege to serve the people of Tasmania in the Australian Senate for over eleven years”.

“I look forward to commencing a new chapter in my professional career, following a short break with my family.”

Before entering parliament in 2007, Bushby was a political adviser, practised as a commercial and international trade lawyer, and was a partner in a public relations firm.

The government leader in the Senate, Mathias Cormann, said Bushby had been a “highly professional and competent” chief government whip as the Coalition had to negotiate legislation through the chamber in which it did not have a majority.

Fellow Tasmanian Liberal senator Eric Abetz said Bushby had been a “champion of all things Tasmanian” as well a “stand-out contributor towards economic policy over the last 11 years, including through his long service on the Senate economics committee”.

The foreign affairs minister, Marise Payne, thanked consul-general Michael Wood – a career diplomat appointed by Julie Bishop in 2015 – “for his contributions to advancing Australia’s interests in Chicago and the surrounding region”.

In 2013, Bishop sacked the former Labor Victorian premier Steve Bracks from his role as consul-general in New York because she claimed the appointment was made by the Gillard government inappropriately close to the 2013 election.