approve, O.K., okay, sanction - give sanction to; "I approve of his educational policies"

warrant, guarantee - stand behind and guarantee the quality, accuracy, or condition of; "The dealer warrants all the cars he sells"; "I warrant this information"

side, root, pull - take sides with; align oneself with; show strong sympathy for; "We all rooted for the home team"; "I'm pulling for the underdog"; "Are you siding with the defender of the title?"

champion, defend - protect or fight for as a champion

second, endorse, indorse, back - give support or one's approval to; "I'll second that motion"; "I can't back this plan"; "endorse a new project"