OTTAWA - Every one of Stephen Harper's cabinet ministers has been told to be in the capital on Monday morning, with signs pointing to a larger-than-anticipated cabinet shuffle as the prime minister moves to re-energize his minority government.

Several Conservative sources indicated Thursday that another of Harper's patented political surprises may be in the works, and that the most senior ministries -- including finance and foreign affairs -- could be in for a housecleaning.

"The best defence is a good offence,'' said one senior source, alluding to a widespread perception that the government has stalled and needs to reassert itself.

The underlying message of a significant shuffle, said one, is of a proactive government.

It's believed a dozen cabinet portfolios will change hands as Harper endeavours to put a new face on his government after a year and a half in office.

The prime minister broadly hinted last week in Charlottetown that a shuffle was in the works.

In addition to having every minister in Ottawa on Monday, their respective communications staffs have been told to be prepared to work over the weekend.

Sources say several of the most senior and important ministries are likely to change hands, including finance, defence, foreign affairs, health, industry and public safety.

Indian affairs and Canadian heritage also appear destined for new leadership.

Even Finance Minister Jim Flaherty, considered to be one of Harper's most secure ministers, is reportedly under review as the government looks for a way out from the twin quagmires of the income trust about-face and the equalization battle with the East.

Flaherty's surprise decision to tax income trusts after the Tories explicitly promised the opposite in the last election campaign continues to sap Conservative support in core constituencies, sources said. And the ongoing fight over resource revenues and the Atlantic accords is pounding Tory fortunes in Atlantic Canada.

Expect the unexpected, said several sources. One move that won't be a surprise is a change at defence.

Pundits and critics have been calling for the replacement of Gordon O'Connor for months, but the more eye-popping change might involve Foreign Affairs Minister Peter MacKay. Sources suggest MacKay could switch portfolios with Industry Minister Maxime Bernier in an effort to allow MacKay to spend more time wooing Atlantic Canadians.

The Nova Scotia MP already has the Atlantic Canada Opportunities Agency under his mantle, and the industry job is thought to be a more natural fit given the Harper government's fractious relationship with the region.

Bernier's name has also come up as a possible replacement for Flaherty.

Jim Prentice, currently at Indian affairs, is widely rumoured to be taking over defence from O'Connor, with Health Minister Tony Clement moving to Indian affairs.

Lawrence Cannon could move from transport to replace Heritage Minister Bev Oda who has been hammered by critics for her performance.

Sources indicate that whatever moves Harper makes, they will likely involve re-shuffling his front bench rather than a significant infusion of new blood.

However one possible cabinet newcomer that gets repeated mention is Calgary backbencher Diane Ablonczy, who is rumoured to be in line for a senior post, possibly the health portfolio. The addition of the veteran parliamentarian would correct one of the notable omissions in Harper's first cabinet.