JOHNSTON, Iowa, Nov. 9 — Senator Barack Obama’s political appeal has always stemmed in part from his biography. For nine months, he has been telling his story in dozens of visits across Iowa, amplified by a multimillion-dollar advertising campaign and a robust network of admirers.
But as voters start narrowing their options in the Democratic presidential race, Mr. Obama is trying to re-establish his story line in the face of misinformation, the long shadow of Senator Hillary Rodham Clinton and perhaps prejudice as well.
“You have e-mails saying that I’m a Muslim plant that’s trying to take over America,” Mr. Obama told voters the other day at a rally in eastern Iowa. “If you get this e-mail from someone you know, set the record straight.”
Now his campaign’s effort to reach Iowans who have received anonymous e-mail messages questioning his patriotism or faith has grown more organized. In each of his 33 state field offices, workers are armed with two letters of rebuttal.
The first is signed by three Iowa ministers, a nun and a church elder, who write, “Senator Obama is a committed Christian who found Christ long before entering politics and has been outspoken about his faith ever since.”
The second, signed by three retired generals, is intended to refute widely circulated e-mail message questioning Mr. Obama’s patriotism by showing a picture of him not placing his hand over his heart while the national anthem played before a political speech.
“Senator Obama’s personal history represents the best of the American Dream,” the letter says. “His grandfather fought in Patton’s army and went to school on the G.I. Bill. His grandmother worked on a bomber assembly line during World War II.”
In the closing weeks before the Iowa caucuses, Mr. Obama is placing a renewed emphasis on his biography as he tries to increase his appeal to working-class voters. Through his life story, he wants to offer himself as more than simply a political alternative to Mrs. Clinton and former Senator John Edwards.
Though previously hesitant to talk extensively about his mother, who died of cancer more than a decade ago, he mentioned her again and again this week in telling voters he understood what it was like to grow up, for a time, with a single mother who relied on food stamps. And her struggle with cancer, he said, taught him about the health care system.
Mr. Obama has now made 32 trips to Iowa, spending 59 days visiting 62 counties. As he passed through more than a dozen cities there this week, many of his crowds were smaller and the settings more intimate, with curiosity seekers giving way to prospective caucusgoers.
“There are still people in every room who don’t know enough about Barack,” said David Axelrod, the campaign’s chief strategist, who traveled with him here this week. “The biography authenticates his message.”
Having spent more than $5 million in television advertising in Iowa, Mr. Obama is embarking on a fresh media offensive. He conducted nearly as many interviews in two days this week as during a two-month stretch earlier this year. He invited Iowa reporters to an off-the-record cocktail session Thursday evening, held a news conference in this Des Moines suburb on Friday and appeared on the public television program “Iowa Press.”
The appearances served as a prelude to the Jefferson-Jackson dinner on Saturday, featuring six Democratic candidates appearing before 9,000 party activists. The campaign is placing enough importance on the event that Mr. Obama, famous for last-minute cramming, has been working for nearly two weeks to memorize his speech. “If you don’t do well in Iowa,” he told reporters Friday, “you’re going to have problems catching up.”
In all these efforts, Mr. Obama is returning to his personal story to demonstrate his outside-the-Beltway experience, illustrate an ability to bring change and elevate his candidacy. At the same time, his campaign is prepared to answer questions that have long shadowed his biography, vigilantly tracking rumors and instructing supporters to catalog e-mail and other materials.
Asked Friday whether his race would affect his candidacy, he said, “I am getting a fair hearing, and I will get a fair hearing.”
Still, the rumors worry some supporters.
“One of the stupidest things I’ve heard and keep hearing is that he’s a Muslim,” said Linda Boston, a member of his state steering committee. “That is not true. He’s a Christian. I would like to see that rumor put to rest.”
At a stop this week in Muscatine, a woman in the crowd noted that she had received many negative e-mail messages.
“We’ve been hearing this for a while now,” Mr. Obama replied, his voice steady. “You don’t have to curse them out. Just tell them that they are misinformed.”