Conservative voters, accusing Leavitt and Sen. Orrin Hatch of abandoning their principles, greeted the governor with shouts of ''Democrat'' and ''hypocrite'' as Leavitt blew kisses to the audience.
Leavitt received 54% of the delegate vote - short of the 60% he needed to avoid a primary. He will have to compete against Glen Davis, a little known Republican who spent just $3,000 on the convention race.
Davis won 46% of the delegates' support.
''I'm not surprised,'' he said. ''We have a governor who claims to be a Republican but has violated many of the principles he claims to cling to.''
Leavitt said he looked forward to spreading his message to voters during his primary.
''(The delegates) have spoken. What they've said is, 'Mike Leavitt. Go out and earn the nomination in a primary,''' Leavitt said. ''Would I rather not have a primary? Yes. Do I have any sense of reluctance about going into a primary? Absolutely not.''
Hatch secured the party's nomination with 61%, but his challenger Greg Hawkins received a surprising 36%. Hawkins was then nominated as Davis' running mate for lieutenant governor.
Rep. Merrill Cook, R-Utah, who holds one of the nation's most vulnerable congressional seats, was forced into a June 27 primary against businessman Derek Smith.
The winner between Smith and Cook will face Democrat Jim Matheson, who accepted his party's uncontested nomination at the Democratic convention Saturday.
National Republican leaders, including House Speaker Dennis Hastert and House Majority Leader Dick Armey, have rallied to Cook's aide to retain their slim 11-seat majority in the 435-member U.S. House of Representatives.