He replaces Kevin Page whose term as budget watchdog expired earlier this year after years of often-bitter squabbling with the government.
Frechette has been employed in the Library of Parliament since 1986 and was senior director of the economics, resources and international affairs division of the library's parliamentary information and research service when named to his new post.
Federal sources said Frechette was one of three people on the Conservative government's short list, and the only candidate given a briefing about the inner workings of the budget office.
Frechette, however, has apparently never been involved in developing or analyzing a federal budget.
The government expressed confidence, however, that he can handle the job.
"Between his training as an economist, his experience in serving parliamentarians and managing others who do, and his respect for Parliament, Mr. Frechette will do a fine job as parliamentary budget officer," government House Leader Peter Van Loan said in a statement.
The position of budget officer was created by the Conservatives following the Liberal sponsorship scandal.
The office was the subject of much political debate when it was run by the often-combative Page.
Opposition parties have accused the Harper government of wanting to convert the position to lap dog from a watchdog.
Page's reports, including an incendiary look at the F-35 stealth-fighter program, provided political ammunition for the Liberals and NDP.
He routinely butted heads with federal ministers, including Finance Minister Jim Flaherty, who accused him of overstepping his authority by wanting to examine and catalogue the extent of federal budget cuts.
Sources have said it was tough to find a candidate for the job from within the federal bureaucracy because the salary offered is equivalent only to that of a mid-level official.
The budget officer is an employee of the Library of Parliament, an institution that operates independently from the government under the management of the parliamentary librarian. The library is accountable through the librarian to the Speakers of the Senate and the Commons.
Frechette's five-year term formally begins on Tuesday.
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