SYDNEY — The dual citizenship crisis that has rocked Australia’s parliament took another twist on Tuesday, with a senior member of the governing Liberal Party saying he may have to quit Parliament.

Stephen Parry, a senator who is president of Australia’s upper house, said he has contacted authorities in the United Kingdom to check if he holds dual citizenship because of his British-born father. He would be the latest lawmaker found to have breached of an obscure clause in the nation’s constitution that bans lawmakers from holding dual citizenship.

The High Court on Friday disqualified five lawmakers from sitting in Parliament on the grounds that they were citizens of both Australia and another country, a breach of the clause that only came to light in July.

The five included Deputy Prime Minister Barnaby Joyce, the leader of the National Party, the junior partner in Liberal’s ruling coalition. Joyce has renounced the New Zealand citizenship he inherited from his father but still must win a by-election if he wants to return to his seat.

Although most lawmakers in multi-cultural Australia have been checking into their citizenship status since the crisis erupted, Parry said he had only examined his own case after the High Court’s decision on Friday.

He said his late father had moved to Australia from Britain as a boy in 1951, and that he was born in Tasmania in 1960. Parry said he had always regarded his father as Australian, particularly as he served in the Australian Army Reserve, but that he had now sought clarification from the British Home Office.

While previous politicians caught up in the crisis had sought legal advice, Parry said last Friday’s verdict made his options clear.

“In the event that I am found to hold British citizenship by virtue of my father’s status, then I will clearly be in breach of Section 44(1) of the constitution and would therefore resign as President of the Senate” and as a senator for the state of Tasmania, Parry said in a statement. “I believe the High Court has made it abundantly clear what action is required.”

Critics have condemned as outdated the 116-year-old constitutional ban on lawmakers having dual citizenship in a country where almost half the people are immigrants or have an overseas-born parent.

One opposition Labor senator, Sam Dastyari, made a joke of the situation on Twitter.

“For Halloween, I’m going to dress up as the constitution and just walk around parliament,” he wrote.