OTTAWA — Prime Minister Stephen Harper plans to fill 18 vacancies in the unelected Senate with Conservative loyalists before Christmas, CTV News has learned.

Sources said Harper is concerned the Senate committee system isn't working properly because there are only 20 Conservative senators sitting in the Liberal-dominated Red Chamber.

But according to insiders, what really drove Harper to move quickly and fill the vacant Senate seats is the possibility of losing political power in January at the hands of the Liberal-NDP coalition.

The centre-left alliance, which is supported by the separatist Bloc Quebecois, is threatening to boot the Tories out of power by voting against their budget bill in late January.

"It would be irresponsible to have this unelected coalition government stack the Senate with their supporters," said one Conservative insider.

Harper had campaigned on replacing the unelected body with elected Senators. Before the fall election, the Tories had proposed legislation to allow for their appointment in provinces that held Senate elections, and limit their terms to just eight years.

Currently, senators in the 105-seat chamber serve until the age of 75.

In a speech to his caucus almost exactly two years ago, Harper said: "Imagine that after a century and a half, democracy will finally come to the Senate of Canada."

Still, it appears Harper hasn't completely backed away from his previous policy. An insider said Harper would ask anyone he appoints to agree to step down and run in a Senate election if new legislation is ever implemented.