The New Democrats are calling for a mid-summer finance committee meeting to discuss "the weakening Canadian economy," and they want Joe Oliver to be there to answer questions.

NDP finance critic Nathan Cullen is leading the charge, writing committee chair James Rajotte, a Conservative MP, to request the meeting and the appearance by the finance minister.

In his letter, Cullen notes the revised budget projections by the parliamentary budget officer that suggest Canada will see a $1-billion deficit at the end of the year.

"This is a significant deviation from the Budget 2015 estimate of a $1.4 billion surplus," wrote Cullen, the committee's deputy chair.

"I believe it is important for parliamentarians to examine the impacts of this dramatic shift in government finances and the weakening Canadian economy."

Call to release updated projections

Parliament's standing orders, or rules, require a committee chair to call a meeting within five days of getting requests from any three members of the committee. The MPs need 48 hours' notice, so the earliest the meeting could happen is Tuesday, according to the NDP.

The NDP's other finance committee members, Pierre Dionne Labelle and Raymond Coté, have also requested a meeting.

While the rules say the committee has to meet once three members make the request, it's not a given that Oliver would have to appear.

A day before the NDP sent their letter, Liberal finance critic Scott Brison wrote Oliver to ask him to appear before the committee.

"You and the prime minister contend that the budget will still be balanced …. The Bank of Canada said we are in a recession this year, and there has been zero economic growth to date in 2015. Canadians deserve honest answers and information from their government," Brison wrote.

"I am also calling on you to make public your department's updated projections on expected revenues and expenditures for 2015-16."

Read Nathan Cullen's letter to James Rajotte.

Read Scott Brison's letter to Joe Oliver.

Follow @laura_payton on Twitter