Just hours before a rally for Barack Obama began at Copley Square in Boston Saturday, the Illinois senator officially announced his bid for president in 2008.

At 45, the first-term senator is the youngest democratic candidate vying for the position so far, with other contenders including Sen. Hillary Clinton, D-N.Y., and John Edwards, former senator from North Carolina.

“I know I haven’t spent a lot of time learning the ways of Washington. But I’ve been there long enough to know that the ways of Washington must change,” Obama said Saturday outside the Illinois State Capital, according to Associated Press reports.

The Copley Square rally was sponsored by the Massachusetts Chapter of DraftObama.org, a volunteer grassroots movement supporting Obama for president.

Speakers celebrating Obama’s announcement included Leonard Alkins, a Boston civil rights advocate, and Samantha Power, a professor at the Harvard Kennedy School of Government who worked in Obama’s office last year.