Pennsylvania Rep. Joe Sestak isn’t fazed by going up against Sen. Arlen Specter, who leads in fundraising and in the polls and has the support of Democratic establishment figures.

Joe Sestak (Alex Wong/Getty Images)

Speaking with reporters on a conference call Tuesday afternoon, a few hours after he made his Democratic primary challenge of Specter official, Sestak said that his political situation today isn’t unlike 2006, when he defeated veteran Republican Rep. Curt Weldon in the 7th District.  

“I love being the underdog,” Sestak said. “A lot of room to grow. Seventy percent of the people don’t know me enough to make a decision, and I’m going to give them that opportunity.”