OTTAWA -- The Conservative government has booked $13.5 million for an all-out, co-ordinated blitz in April and May to advertise its 2015 pre-election budget.

The push, detailed in internal government documents obtained by The Canadian Press, builds on existing Finance Canada and Canada Revenue Agency campaigns to promote Conservative tax measures both past and proposed -- the backbone of the Harper government's re-election strategy.

"Phase VIII" of a CRA campaign entitled "Tax Relief Measures" comes with a $6-million budget this fiscal year and is described as a "continuation of the 2014-15 ad campaign."

The ad buy is listed as a bulk purchase of TV for April, a "heavy-up" April TV buy and an "April 2015 NHL (TV)" buy.

Playoff hockey fans will have seen the publicly funded campaign.

"The intention is to encourage taxpayers to claim the tax relief measures to which they may be entitled and file their tax returns online and on time," says the internal government ad description.

It comes as Finance wages a $7.5-million campaign broadly described in a February document as illustrating how the budget "is on track to positioning Canada for success in the 21st century global economy through a series of measures."

How will the government illustrate that success? By promoting tax benefits, the internal government campaign description suggests.

Two radio ads under the "EAP Jobs and Growth Radio campaign (Winter 2015)" show that the April spots "consist of a similar message as the CRA's Tax Filing campaign which is currently on air via TV, Internet and print."

In all, Finance and the tax agency have booked $13.5 million in 2015-16 to promote last week's federal budget. A federal election must be held by Oct. 19.

Those pocketbook-focused ads are augmented this month by a heavy buy of military recruitment ads, which dovetail with the Conservative government's anti-terrorism and security messaging. The cost of the National Defence department ad campaign for 2015-16 is not yet known.

The spring ad blitz comes amid increasingly vocal opposition to the Harper government's use of taxpayer-funded advertising.

The Liberal party used an opposition day motion Monday to debate ending "wasteful spending on partisan government ads."

A private member's bill by Liberal MP David McGuinty proposes to have all government advertising cleared in advance by the auditor general's office to ensure it is informative and non-partisan.

McGuinty's brother, former Ontario premier Dalton McGuinty, presided over the introduction of a similar provincial law in 2004 that gave the province's auditor the job of scanning ads for partisanship before they were released.

"The prime minister cynically preaches restraint, yet he's spent more than $750 million (since 2006) on ineffective and wasteful partisan advertising," McGuinty charged Monday in the daily question period.

The government has a responsibility to tell Canadians about tax measures, countered Labour Minister Pierre Poilievre. Some 200,000 eligible families must sign up for enhanced benefits in order "to get that July lump-sum payment," he said.

"The Liberals don't want those parents to get any of that money," said Poilievre. "In fact, the Liberals would take it all away and that's why they're against us informing families that those benefits exist."

The Liberals have said they would rescind a proposed income-splitting tax measure but would not reverse the increases to the child tax benefit.

New Democrats, meanwhile, responded to the Liberal opposition day motion by issuing a release citing the $953.6 million spent on government ads under the Liberals between 1998 and 2006.

As a result of revelations about the federal sponsorship scandal, ad spending by the Liberals dropped dramatically in their last three years in office, averaging $53.5 million a year.

Under the Conservatives, ad spending averaged about $84 million a year through 2014, according to figures compiled from annual advertising reports and government estimates.