Willingham entered Thursday night's game against the Yankees tied for the AL lead in homers with five, along with a team-leading nine RBIs.
"I try to out there with a simple approach and look for something good to hit," Willingham said. "I've hit a few of them hard, and the ones that I've hit hard have found some holes, so I think that's key.
"I've also pulled all my homers, and generally when you hit the ball hard and you pull, it goes out. So hopefully, if I keep squaring up the ball and getting it into the air, it'll keep going out of the ballpark."
Willingham is joined on the ballot by longtime Twins such as Joe Mauer, Justin Morneau and Denard Span. But it marks the first time that Morneau is listed as a designated hitter.
The online ballot will launch on Friday. Fans can cast their votes for starters up to 25 times at MLB.com and all 30 club sites -- online or using a mobile device -- using the 2012 All-Star Game MLB.com Ballot until Thursday, June 28, at 10:59 p.m. CT.
Mauer and Morneau are both four-time All-Stars, while Willingham and Span have never been selected to play in the Midsummer Classic.
Other Twins on the ballot are first baseman Chris Parmelee, second baseman Alexi Casilla, shortstop Jamey Carroll, third baseman Danny Valencia and outfielder Ben Revere, who was optioned to Triple-A Rochester on Saturday. Ryan Doumit, who has seen time in right field and behind the plate, is not on the ballot but can be voted in as a write-in candidate.
The All-Star Game is slated for July 10 at Kauffmann Stadium in Kansas City.