OTTAWA -- Four NDP provincial politicians from British Columbia are urging Prime Minister Justin Trudeau to call a byelection in the federal riding of Burnaby South, where federal New Democrat leader Jagmeet Singh wants to run for Parliament.

The letter, by Anne Kang, Katrina Chen, Raj Chouhan and Janet Routledge, who all represent Burnaby districts, says the politicians are disappointed that Trudeau has yet to call a race in the riding vacated by former B.C. NDP MP Kennedy Stewart.

Stewart is now the mayor of Vancouver.

"Canadians deserve strong representation at all three levels of government," the letter, dated Nov. 9, says. "In that regard, we are disappointed with your decision in delaying the call of the federal byelection in Burnaby South, leaving constituents we represented without a voice in Ottawa."

In late October, opposition leaders also joined forces to press Trudeau to call byelections in all four vacant federal ridings in the House of Commons.

Four leaders -- the Conservatives' Andrew Scheer, New Democrats' Jagmeet Singh, Greens' Elizabeth May and the Bloc Quebecois' Mario Beaulieu -- sent a letter to Trudeau objecting to his decision to call a byelection in just one of the four ridings.

Earlier in the month, Trudeau called a byelection for Dec. 3 in the eastern Ontario riding of Leeds-Grenville-Thousand Islands and Rideau Lakes, which had been vacant almost six months following the death Conservative MP Gordon Brown.

The prime minister said the other three ridings had been vacant for "mere weeks" and will call the byelections in due course. He must call a byelection within six months of an MP leaving a seat open.