WASHINGTON (AP) - Sen. Barack Obama launched a presidential campaign yesterday that would make him the first black to occupy the White House, and immediately tried to turn his political inexperience into an asset with voters seeking change.

The freshman Illinois senator - and top contender for the Democratic nomination - said the past six years have left the country in a precarious place and he promoted himself as the standard-bearer for a new kind of politics.

"Our leaders in Washington seem incapable of working together in a practical, commonsense way," Obama said in a video posted on his Web site. "Politics has become so bitter and partisan, so gummed up by money and influence, that we can't tackle the big problems that demand solutions. And that's what we have to change first."

Obama filed paperwork forming a presidential exploratory committee that allows him to raise money and put together a campaign structure. He is expected to announce a full-fledged candidacy on Feb. 10.

Obama's soft-spoken appeal on the stump, his unique background, his opposition to the Iraq war and his fresh face set him apart in a competitive race that also is expected to include front-runner Sen. Hillary Rodham Clinton of New York.

Obama has uncommon political talents, drawing adoring crowds even among the studious voters in New Hampshire during a much-hyped visit there last month. His has risen on the force of his personality and message of hope - helped along by celebrity endorsements from the likes of Oprah Winfrey, billionaire investor Warren Buffett and actors Matt Damon and Edward Norton.