OTTAWA - First a sleepover, now a double-dog dare.

Punchy MPs, bleary-eyed from their all-night vote marathon, were exchanging rhetorical blows Friday in the House of Commons over the election-spending headaches of Conservative attack dog Dean Del Mastro.

The Ontario MP, who normally defends the Conservatives against accusations of dirty electoral tricks, finds himself caught up in Elections Canada allegations that he spent too much during the 2008 campaign and then tried to cover it up.

Liberal MP Scott Andrews repeated the allegations during question period as he called Del Mastro — who is Stephen Harper's parliamentary secretary — on the carpet, even though he wasn't in the House to defend himself.

"The prime minister and his parliamentary secretary can no longer fabricate spin around the fact that serious Elections Canada rules have been broken," Andrews said.

"Let us be clear, it is about the documents he did not submit. The facts are, the member was responsible for filing forged documents. The member took steps to hide the truth about spending limits."

That got Tory MP Pierre Poilievre on his feet, urging Andrews to take it outside — and giving question period a distinct schoolyard flavour.

"A lot of people watching may not realize that parliamentary privilege protects this member so he can say anything he wants without ever having to prove it," Poilievre said.

"He can disparage anybody's reputation and he never has to back up any of his allegations with facts. He has made some very clear ones. He has no evidence to back them up.

"I would encourage him, if he has the integrity, if he has the courage, to take the exact statement that he just made, walk outside in front of the media and repeat those allegations. It is my bet that he will not do it."

Court documents filed by an Elections Canada investigator allege Del Mastro's campaign filed a false document to the agency. The MP's official agent, Richard McCarthy, is also under investigation.

None of the claims have been proved in court, and Del Mastro insists Elections Canada never contacted him about his campaign return.

The matter revolves around a contract for polling and research.

In court documents, Elections Canada says Del Mastro paid Holinshed Research Group $21,000 out of his personal bank account. But the Peterborough MP's campaign return shows only $1,575 was paid to the company.

"I believe that Dean Del Mastro ... took steps to hide the true nature of the transaction by paying the $21,000 election expense from his personal bank account ... and obtained a false invoice from Holinshed in December 2008 ... which was never paid to Holinshed as no services were provided by Holinshed," the court document says.

"Dean Del Mastro then submitted this invoice to the campaign and was reimbursed $1,575 ... for a contract which he never paid."

Elections Canada further alleges Del Mastro took those steps to "deceive" an auditor "into a false belief that the election expense of 'election surveys or other surveys or research' was only $1,575 and not $21,000 as stipulated in the contract."

Del Mastro's lawyer did not return a call for comment.

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• Here are five questions raised by Dean Del Mastro's 2008 campaign spending:<br><br>(CP)

• 5. Was He Reimbursed For The $21,000 Personal Cheque

  Federal election spending laws say candidates can contribute $2,100 to their campaigns, a tenth of the amount in question. Del Mastro says his campaign or his riding association reimbursed him for any election expenses, but records on the website of Elections Canada show no sign of a repayment that big. The records show the campaign reimbursed Del Mastro a total of $437.54 for his 2008 run. Likewise, the expenses filed by the riding association show $96,670 in transfers to Del Mastro's campaign, but none to him. (Shutterstock)

• 4. Why Isn't The $21,000 Paid To Holinshed Research Group Listed In The Election Return?

  After a 2009 falling-out over a contract with Del Mastro, Frank Hall, president of Holinshed Research Group, filed a suit in small claims court. The claim was dismissed as abandoned June 8, 2011, meaning Hall let it lapse. But the records he filed in the claim are still available. They show a $21,000 invoice, as well as the personal cheque from Del Mastro. The Sept. 14, 2008 invoice lists 630 hours of voter identification phone calls, plus election day get-out-the-vote calls. But the Elections Canada return lists only two Holinshed expenses: one for $10,000, categorized in a miscellaneous "amounts not included in election expenses" category, and another for $1,575 for election surveys or other research. (Alamy)

• 3. What Happened To The Other $11,000?

  If the $10,000 Holinshed expense listed in the campaign costs comes from the $21,000 invoice, Del Mastro's campaign has up to another $11,000 unaccounted for. (Alamy)

• 2. How Does The $21,000 Fit In Under The Spending Limit?

  Del Mastro's campaign spending limit was $92,566.79. The expenses he submitted to Elections Canada show he spent $90,987.52 or 98.29 per cent of his cap (before the election agency reviewed and got more detailed information from him, records showed he spent $91,770.80, or 99.14 per cent of his cap). Elections Canada records suggest that if the $21,000 invoice is included, he would have exceeded the limit. Del Mastro did not explain the additional $21,000. (CP)

• 1. What Happened To Holinshed?

  The Ottawa-based research and polling company appears to be out of business, with its website out of service and its phone disconnected. The firm did work for at least 10 federal Conservative candidates in the 2008 election, and worked with Ontario Progressive Conservatives as well. As the CBC's Kady O'Malley pointed out last fall, Holinshed got $125,000 from the federal government to develop GeoVote, a voter ID system. The cash was part of the Canada Economic Action Plan. The project website says the money was to develop "the firm's flagship application GeoVote used in support of election campaigns and data management used in preparation for upcoming elections." It also seems to be the only political polling firm to have got stimulus money. (Alamy)