Former Sen. Paul Tsongas of Massachusetts said Tuesday his Iowa campaign swing persuaded him to enter the Democratic presidential race and he'll soon formally announce his candidacy.

"I needed a live audience in a state that was new to me to get the reaction," Tsongas said.He is the first Democrat to speak so directly about challenging President Bush.

He met Monday with Democratic activists and said he came away convinced that his ideas will get a warm reception in the state.

"Last night was, I guess, in my head the last major obstacle," Tsongas told reporters. "Now it's just a matter of just going through the procedural ritual.

Tsongas left the Senate in 1985 after a bout with cancer, which he said he has since conquered.