In a sharp break from their first two mandates, the Harper Conservatives are preparing to unveil a budget that is revolutionary rather than evolutionary, one that will introduce sweeping structural changes in key areas of federal policy. Politically, from the government's standpoint, that won't happen a moment too soon — even if the budget provokes great controversy, which it most certainly will.

Whether in trade, immigration, retirement benefits, resource development, innovation or fiscal policy, Conservative insiders say, the years of plodding, minority-era "incrementalism" are over. Indeed, there's a sense within Conservative ranks that their moment of truth, a chance to distinguish themselves from the other parties in stark terms and establish a lasting legacy, has arrived.

"Everybody's going to be busy for a long time reporting about it," said one insider, speaking of the coming budget, to be handed down by Finance Minister Jim Flaherty on March 29.

The subtext: Unless the robocalls scandal mutates like a super flu into something as-yet-unseen — specifically, unless evidence emerges that the Conservative Party or its national campaign knew about or participated in electoral fraud, something the prime minister and campaign chair Guy Giorno have categorically denied — it may soon be knocked off front pages by more wrenching debates.

Government sources characterize the coming shift as moving from day-to-day governing, extracting successes wherever possible, to making fundamental changes that correct big, underlying problems in the economy, or open up new opportunities in broad areas, such as resource development or trade. In a sense the Tories are adopting something closer to the style of earlier Conservative governments, such as the Brian Mulroney regimes that introduced North American free trade: Go big or go home.

These changes, and the strategy underlying them, were first flagged by the prime minister in his "OAS shocker" speech in Davos, Switzerland, in January. At the time most attention focused on Stephen Harper's revelation that the government was considering a fundamental overhaul of retirement benefits, in order to make them sustainable long-term, despite the aging baby boom. That might even include a rise in the age of eligibility for Old Age Security from 65 to 67, Harper indicated.

The Liberals and New Democrats, too predictably, immediately cast this as an attempt by the harshly cold, callous Conservatives to seize income from silver-haired widows and hand it over to weapons manufacturers. That debate, callow as it was, was swept aside by the backlash over Bill C-30, the online access bill, then Vikileaks and then robocalls, which continues to dominate political discussion in Ottawa.

What's interesting about the government's intentions now, heading into the budget, is how determined the Conservatives are to press ahead with a full suite of significant reform, controversies be damned — and how far the plan extends beyond the OAS system. The change envisioned is huge.

For starters, the age of eligibility for OAS will indeed rise from the current 65 to 67 (though in grandfathered fashion, so that only those younger than 50 or so now will be affected), sources confirm. Beyond that, immigration, resource development, research and innovation and trade are also being overhauled, all while the government moves more aggressively than previously signalled to balance the books. (The Finance department has said budget cuts will be in a range between $4 billion and $8 billion. As I reported here last week, the overwhelming majority of Tory ministers and MPs are pushing hard for cuts at the very upper end of that range, because they want to campaign in 2015 on a balanced budget.)