The federal New Democrats are pitting a former Saskatchewan finance minister against the incumbent federal minister in the Toronto riding of Eglinton-Lawrence, in a bid to shore up the party's credibility on the economic front.

NDP Leader Tom Mulcair was confident that Thomson can defeat Conservative Joe Oliver, but the NDP has never done well in the riding.

"The NDP's Andrew Thomson offers the people of Eglinton-Lawrence something that Joe Oliver hasn't — a record of balanced budgets," Mulcair said.

Mulcair said he'll take Thomson's economic record in Saskatchewan over that of Oliver and Prime Minister Stephen Harper any day.

As finance minister in Saskatchewan, Thomson brought in big tax cuts in 2006 and skirmished with the federal government over equalization payments.

Mulcair said an NDP government would give Parliament's budget officer more powers so Canadians have a much better window into the budget process.

"Our plan will enshrine budget transparency into law," Mulcair said as he announced the policy at a campaign event in Toronto.

The New Democrats would protect the budget watchdog from political interference and force government departments and agencies to make financial information available, he added.

"We'll remove the prime minister's power to fire the parliamentary budget officer and make them an independent officer of Parliament, like the auditor general," Mulcair said. "We'll make transparency the law so that future governments can't hide financial information from Canadians."

Before he became prime minister, Stephen Harper promised an independent budget authority, greater accountability and transparency in the budgeting process, and said he would force ministries to disclose information, noted Mulcair.

"But he's failed to deliver on every single one," he said. "Stephen Harper went out of his way to undermine the independence of the office, fighting the parliamentary budget officer in court to prevent the release of budget details."

Harper's Conservatives clashed often with former parliamentary budget officer Kevin Page, starting in 2008 when he warned of a recession and possible deficits, but an economic update from the Tories indicated no recession and no budget shortfalls.

Page got under the Conservatives' skin again in 2011 when he said the cost of the F35 fighter planes would be significantly more expensive than the government had been stating. And in 2012, he disagreed with Harper's decision to raise the eligibility requirement for Old Age Security payments and disputed the Conservatives' conclusion that the program was not sustainable. His assessment of the OAS was called "unbelievable, unreliable, incredible" by then-finance minister Jim Flaherty.

Page even sued the Conservative government in 2012 over its refusal to provide information on budget cuts, staff reductions and other austerity measures.

The NDP leader also said testimony from Harper's former chief of staff, Nigel Wright, at Mike Duffy's trial, shows many people in the prime minister's office knew Wright cut a $90,000 cheque for the senator to pay back expenses billed to taxpayers.

"Mr. Harper would have us believe that these were rogue elements within his office who did this without letting him know anything about what was going on," said Mulcair. "But the thing, is if they were out of control and not reliable people ... how come he's kept them all in his office? That's just not credible."

Mulcair also lashed out at Harper for gutting environmental protections and trying to ease the approval process for projects like the Energy East pipeline, which he said ended up making it harder, not easier, to get them started.

"Stephen Harper poisoned the well," he said. "He thought he was helping these companies get their projects faster, but in fact not one of them has gotten off the drawing board."

The NDP would introduce a new approvals process for big energy projects and would start over again with Energy East, added Mulcair.

"You can't say 'Yes' to Energy East or any other project right now because the public simply can't have confidence (in the process), he said. "So the first thing we'll do is put back the process, and re-start Energy East under that credible process."