A customary ceremonial practice has been for the losing candidate ( s ) in the primary season to " release " their delegates at the convention and exhort them to vote for the winning nominee as a sign of party unity . Thus , the vote tallied on the convention floor is unanimous or nearly so . For example , during the 2008 Democratic National Convention , Hillary Clinton ( who only captured about 22 percent of delegates compared to Barack Obama 's approximate 72 percent ) moved to nominate Obama by acclamation , making it a unanimous vote
2008 Democratic National Convention
2008 Democratic National Convention
United States presidential primary