OTTAWA -- The federal Liberals and NDP say conservative politicians are displaying a pattern of attacks against Speakers' independence, an allegation the Conservatives in Ottawa strongly deny.

The accusation comes a day after the federal Conservatives tried, and failed, for the third time to get House of Commons Speaker Greg Fergus to resign over allegations he is too partisan for the role.

Their attempts are designed to intimidate and delay House work, government House leader Steven MacKinnon said.

"The fact is that this culture of intimidating the chair is something we have seen in other legislatures and I think Canadians are rightly horrified by it," he said.

His NDP counterpart Peter Julian said there's a "disturbing undercurrent" in Ottawa and in Saskatchewan by conservatives who are attacking independent institutions, with their latest target being Speakers.

Julian drew a connection to Saskatchewan by linking Jeremy Harrison, former Saskatchewan Party House leader to federal Conservative Leader Pierre Poilievre. Both were elected to Parliament in 2004 as Conservatives. Harrison served one term in Ottawa before being defeated in 2006. He was elected provincially in 2007.

While Poilievre is undermining the Speaker in Ottawa, Harrison is doing the same in Regina, Julian charged.

"It's a pattern now," he said to The Canadian Press.

On May 16, Saskatchewan's Speaker Randy Weekes accused several Saskatchewan Party members and staff, including Harrison, of intimidation, including sending him harassing text messages about his rulings. Weekes is also an elected Saskatchewan Party MLA and served briefly in cabinet, but speakers by custom do not sit with their party caucuses after assuming the Speakers's chair.

Weekes also said Harrison once sought permission to bring a gun into the legislature. Harrison initially denied the allegation but resigned last week after admitting he had forgotten about the incident which happened more than a decade ago.

"The disturbing undercurrent as we see in Saskatchewan, as we're seeing here, is attacks on independent institutions," Julian said.

"And this isn't something we've seen before from Conservatives, but since Mr. Poilievre has become leader we're seeing this more and more."

A spokesperson for Poilievre rebuked Julian's connection.

"This is something that happened in the Saskatchewan Legislature regarding an entirely different party and has nothing to do with the Parliament of Canada and its Liberal Speaker or the Conservative Party of Canada," said Sebastian Skamski, a spokesperson for Conservative leader Pierre Poilievre.

"This is just another pathetic, desperate attempt by the coalition NDP to distract and play defence for Justin Trudeau and their Liberal masters."

The Conservatives argue that Fergus has proven himself to be biased, including ejecting Poilievre from the House of Commons last month for refusing to retract his comment calling Prime Minister Justin Trudeau a "wacko." Fergus was forced to pay a $1,500 fine and apologize after he delivered a partisan tribute to an outgoing interim Liberal leader in Ontario on a video played at the party's leadership convention.

The Liberals apologized to Fergus earlier this month after an invitation to an event in his riding was posted with language attacking the Conservatives. They said the invite was posted by a party staffer using boilerplate terms by mistake. It was replaced.

That incident is what prompted a Tory motion to oust Fergus, which failed Tuesday when the Liberals and NDP voted against it.