The ongoing battle over now-shuttered NDP satellite offices is expected to resume behind closed doors on Tuesday morning, CBC News learned.

Although it's not listed on the official parliamentary agenda, Hill sources confirmed to CBC News that the secretive all-party Board of Internal Economy charged with overseeing MP and caucus spending is scheduled to meet for the first time since July 22, when the NDP turned over a raft of new information related to the cost of the controversial out-of-town outposts.

The party has been under investigation since it came to light earlier this year that it used its House of Commons budget to pay for some staff working out of party offices in Montreal, Quebec City and Toronto, with plans to do the same in Saskatchewan.

Last month, John Duncan, the Conservative whip and chief board spokesman, told reporters that members had deferred the matter of the satellite office issue while they undertook a "careful review" of the documents provided by the NDP.

It appears that review has been completed, which means the NDP may soon get an idea of just exactly how much they'll be asked to pay back to the House of Commons for expenses retroactively deemed inappropriate. 

Depending on how far the board wants to go in clawing back funds already paid out for salary expenses related to those offices, the final tab could easily hit six digits.

NDP to push for public meeting

Last time the board was slated to get together to discuss the satellite offices, the New Democrats made an unsuccessful attempt to open the session up to the media.

According to NDP spokeswoman Greta Levy, the party intends to launch a similar bid tomorrow morning, although it may be difficult for reporters to cover the goings-on - even outside the meeting room itself, as it is located in a part of Centre Block not normally accessible to journalists.

In a letter sent to his fellow board members Monday afternoon, New Democrat MP Philip Toone, who is one of two NDP representatives on the panel, reiterated his party's desire to open the meeting to the public and the press.

"I fully expect that the information that we provided to the board at the last meeting will exonerate us of any partisan charges," he wrote. "But the public will not be able to judge that for themselves since the board continues to have meetings behind closed doors."

He also called on his colleagues to "recuse themselves from taking on such blatant partisan determinations," and called for "the job of fact finding" to be handed over to an "independent body."

NDP MPs already facing repayment demands for mailings

In June, 23 New Democrat MPs, including leader Tom Mulcair, found themselves on the hook for more than $1 million in mailing costs after the board concluded that thousands of mass mailings sent out by party members should not have been covered by their parliamentary office budgets. 

The NDP dismissed the decision as the biased verdict of a partisan-controlled "kangaroo court," and has already served notice that it plans to take the matter to court.

The board is made up of MPs from all parties — three Conservatives, two New Democrats and one Liberal — and chaired by House of Commons Speaker Andrew Scheer.

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