MELBOURNE • Australia's embattled Deputy Prime Minister, under pressure over an extramarital affair, yesterday faced a call to step down as leader of his party - the first such call from a member of the party, which is part of the ruling coalition.

Mr Barnaby Joyce who has campaigned on "family values" and who has been married for 24 years, refused to resign when it was made public that he was expecting a child with a former staff member.

"He needs to step down as leader of the National Party, take a step back into the backbench for a time," Mr Andrew Broad, a Member of Parliament from Mr Joyce's National Party, told state-owned broadcaster ABC.

The National Party is in a ruling coalition with Prime Minister Malcolm Turnbull's Liberal Party. The coalition holds a one-seat majority in Parliament.

Mr Turnbull has called 50-year-old Mr Joyce's affair a "shocking error of judgment". Several of his party members have called for Mr Joyce's resignation.

Mr Broad said he would take up the issue of Mr Joyce's leadership at a party meeting in the capital, Canberra, next Monday.

He said his decision was influenced by the fact that Mr Joyce was unable to serve as acting prime minister while Mr Turnbull is in the United States for an official visit this week, with the Deputy Prime Minister instead taking a week of personal leave.

"I need to know as a Member of Parliament that the person who is going to be the acting prime minister has got their mind on the job," said Mr Broad. "At this point in time, it is not fit for Barnaby to... step up as acting PM.

His call is the latest sign that support for Mr Joyce from within his rural-based party is eroding, amid concern that disapproval of the affair could undermine support in state elections. A state branch of the party withdrew its support for Mr Joyce this week because of the affair.

Two-thirds of voters want Mr Joyce to resign over the affair, according to the Australian newspaper's Newspoll.

REUTERS, XINHUA