Longoria received 35 percent of the vote, and he was followed by Albert Pujols of the Cardinals (9 percent), Tim Lincecum of the Giants (7 percent), Hanley Ramirez of the Marlins (6 percent) and Ryan Braun of the Brewers (5 percent).
Players could not vote for their own teammate in the poll.
Pujols, who is a Triple Crown threat this season and appears to be a first-ballot Hall of Famer, likely did not register higher in the voting due to the fact that he is 29 years old and is in his ninth season.
The rest of the top 10 are 26 years old or younger.
Longoria, who was the 2008 American League Rookie of the Year Award winner, entered Tuesday night's game against the Yankees with the second-most RBIs in the Junior Circuit with 75.
Lincecum, the National League Cy Young Award winner last season, leads the Senior Circuit in strikeouts this season with 183; he had a league-best 265 K's in 2008.
Bill Chastain is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.