When the Conservatives joined with the Liberals in voting to publicly sanction the NDP over its 1.8 million mailings into ridings facing June 30 byelections, they may have been dishing out payback to the NDP, but at the risk of aiding their traditional arch-rivals, the Liberals.

The three political parties all designate some of their MPs to sit on the clubby and secretive Board of Internal Economy, the MPs' committee that rules on how all members of Parliament spend money and resources.

Earlier in June, the board decided that 23 NDP MPs should repay up to $1.17 million for the cost of envelopes and postage. The mailings were sent just before byelections were called in four ridings, and the board said they were improperly "prepared by and for the benefit of a political party."

In a highly unusual move, the board also made its decision public. Usually, when MPs have to repay inappropriate expenses, the board allows them to do so under a cloak of secrecy, a tradition that stretches back to 1868.

The members of the board — four Conservative MPs, two NDP MPs and one Liberal — must take oaths of confidentiality.

Unprecedented attack

Peter Julian, the NDP's House leader, said in a phone interview Friday that the public attack by the normally consensual board is unprecedented.

"But a lot of things are unprecedented," he said. "We've never seen an attack on the Chief Justice [Beverley McLachlin] before."

An NDP staffer who didn't want to be quoted said conversations he's had with Conservative staffers lead him to believe the full-scale barrage against the NDP was "payback time" for the Tories.

He said Conservatives were stung when NDP Leader Tom Mulcair adopted a prosecutorial style of short accusatory questions  — barked at Prime Minister Stephen Harper — over the Senate expenses scandal and a secret private payment by Harper's chief of staff Nigel Wright to Senator Mike Duffy.

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NDP Leader Tom Mulcair roasted Prime Minister Stephen Harper in question period over the Senate expenses scandal. Is it payback time? (Adrian Wyld/Canadian Press)

Independent MP Brent Rathgeber, who used to be a Conservative MP before he quit the Conservative caucus because of what he sees as the government's lack of transparency, agrees.

In a phone interview, Rathgeber said that the Liberal move to join with the Tories in acting as judge and executioner is "a no brainer."

In many ridings, particularly in Ontario in the last election, the Conservatives won former Liberal ridings because of a  vote split between the Liberals and the NDP.

He sees the attack as "a wide tactical move to try to knock the NDP off their perch of being above everything, always. And they like to portray themselves as boy scouts."

He continued, "They've never been in government federally, so they've never had access to sponsorship funds like the Liberals did, they've never been able to appoint people to the Senate and have to bear all the baggage of the Mike Duffys and the Pam Wallins of the world."

Rathgeber thinks the ganging up has become out of control and could hurt the NDP financially, especially if it has to repay even more money over the satellite offices outside Ottawa employing NDP parliamentary staffers allegedly doing party work.

If the amount owing reaches $2 million or $3 million, "that's a whole campaign," Rathgeber said. "That's the cost of renting a plane for five weeks, and then some."

Hurting the NDP could help the Liberals, he added, saying in his area (Edmonton-St. Albert) the NDP used to run second but has now fallen back to third.

Rathgeber's presence in Edmonton-St. Albert in the 2015 election will split the vote even further, since he intends to run as an Independent.

Board dominated by Conservatives

Julian thinks the Board of Internal Economy is dominated by Conservatives and Liberals who "defend themselves for using taxpayers' money to conduct partisan attacks, but then cobble together rules to go after the NDP." He adds the NDP is using mailings to talk about "much more positive things."

Julian said he receives complaints from NDP supporters in various ridings about material mailed by Conservative MPs attacking either Mulcair or Liberal Leader Justin Trudeau.

Last year former interim Liberal leader Bob Rae used his MP's free postage privilege to send letters to NDP ridings.

One Rae mailing sent to the riding of Toronto-Danforth accused its MP, the NDP's Craig Scott, of making it "easier to break up the country" because of the NDP's position that a 50 per cent plus one vote would be sufficient to win a referendum on Quebec independence.

A few years ago, Conservative MPs sent mailings to Liberal MP Irwin Cotler's Montreal riding accusing Liberals of supporting anti-Semitic policies, and praising Conservatives for defending Israel. Cotler is Jewish.

The Board of Internal Economy did not financially sanction the MPs who sent partisan mailings.

The NDP mailings, many sent just before the byelection in the Montreal riding of Bourassa was called, touted NDP policies such as a minimum federal wage and affordable housing. The board contends the NDP was using parliamentary resources to promote the party.

The NDP intends to fight the request that it repay the costs of its mailings in Federal Court. It continues to advocate, as it has for the past year, that the Board of Internal Economy be abolished and replaced with an independent oversight body.