WASHINGTON (Reuters) - Former U.S. Senator Rick Santorum won the Republican presidential primary in Oklahoma on Tuesday, Fox News projected shortly after polls closed.

It was the first victory of the night for Santorum, a staunch conservative who has been trying to establish himself as the conservative alternative to the more moderate front-runner Mitt Romney. Ten states are voting in nominating contests on Super Tuesday.

(Reporting by Deborah Charles and Emily Stephenson; Editing by Vicki Allen)