Youth voters gather outside the Harvard Square subway station to participate in the “I Decide” voter awareness campaign yesterday.

What do you do if you’re worried your vote doesn’t count? For two Winthrop House seniors from California and Massachusetts, the answer was obvious: start a national youth mobilization campaign.

Roommates Leslie S. Bishop ’05 and Rebecca Leventhal ’05 founded the non-profit, non-partisan, “I DECIDE” six weeks ago with the help of Winthrop Master Stephen P. Rosen ’74 and other members of the House.

The group began by selling “I DECIDE” t-shirts at Harvard and on the internet, and each sale also paid for a second shirt to be sent to universities in swing states to encourage students there to vote. The pre-election push culminated in a rally yesterday outside the Harvard T station, drawing 50 to 60 students from around the Boston area.

Each participant called students in Pennsylvania, Florida and Ohio, urging them to vote and then asking them to call three more of their friends in what amounted to a massive phone tree.

The atmosphere was festive, with musicians playing on top of the T stop and TV trucks waiting nearby. Tourists and passersby were curious about I DECIDE, and many bought shirts or called swing states.

“It’s ridiculous that only 30 percent of registered youth voters turn out at the polls,” said Devin Lyons-Quirk ’05, who volunteered to make calls on his cell phone. “It’s easy to just make three phone calls to help fix this problem.”

Boston College sophomore Lindsey A. Keefner came all the way to Harvard Square to call. “It is important for youth to vote because we are the ones who are going to have to deal with the decisions made in the next four years,” she said.

The callers received varied responses from the swing-state voters.

“I talked to people who had already sent in their absentee ballot and who were really excited about voting, but I also talked to people who don’t believe in voting, are not registered and don’t care,” said Margo B. Hoppin ’05.

Though Bishop and Leventhal had expected 300 students to show up, they said they were pleased with the event despite the small numbers.

“Everyone who showed up was so excited to call that we got through all the phone numbers we had despite the low turnout,” said Bishop. “Also, a lot of kids took numbers to call later, so more people were involved than were actually there calling.”

In addition to the rally yesterday, the I DECIDE campaign has spread around the country, gaining national media attention. Over 3,000 shirts have been sold.

Bishop and Leventhal said they wanted to come up with a way for students from non-contested states to influence the election by partnering with students in swing states.

“We then went down and did an event at Penn State and the shirts were really hot and it just took off: our first 400 shirts went in 30 minutes,” Bishop said. “We got a lot of publicity through the Penn State Collegian and local news, and a few days later they ordered 1,000 more shirts.”

At Penn State, hundreds of people wore their shirts to events featuring Michael Moore and Fox News’ Mike Gallagher. Since then, Bishop and Leventhal were featured in Newsweek, and made it on to CBS’s “The Early Show.” They have also been contacted by ABC’s Barbara Walters, who requested t-shirts for the cast of “The View.”