CEDAR RAPIDS, Iowa (CNN) -- Saying she felt compelled to support "the man I believe has a new vision for America," Oprah Winfrey spoke passionately about Democratic presidential hopeful Barack Obama at two rallies in Iowa Saturday.
Oprah Winfrey joins Democratic presidential candidate Barack Obama at a rally in Des Moines, Iowa, Saturday.
"I've never taken this kind of risk before nor felt compelled to stand up and speak out before because there wasn't anyone to to stand up and speak up for," Winfrey told thousands of people in Cedar Rapids Saturday evening.
"We need a president who can bring us all together," she said. "I know [Barack Obama] is the one."
Earlier in Des Moines, she focused on world affairs. Watch Winfrey endorse Obama »
"These are dangerous times, you can feel it. We need a leader who shows us how to hope again in America as a force for peace," Winfrey told the enthusiastic crowd.
"I believe Barack Obama will bring statesmanship to the White House," she said. "He's a man who knows who we are and knows who we can be."
Winfrey said she has voted for as many Republicans as she has Democrats over the years, so her endorsement wasn't about partisanship.
"This is very, very personal. I'm here because of my personal conviction about Barack Obama and what I know he can do for America," she said to applause.
Winfrey also told the crowd that she's looking for more than a candidate with "experience in the hallways of government."
"I challenge you to see through those people who try to convince you that experience with politics as usual is more valuable than wisdom won from years of serving people outside the walls of Washington, D.C.," she said.
Obama thanked Winfrey for drawing a big crowd and coming out to the event.
"There are some people here who are here to see Oprah. I'm sort of a by-product of that and I appreciate that, but what I know is that for her to take the risk of stepping out of her comfort zone is extraordinary," the senator from Illinois said.
Before Winfrey's speech in Des Moines, her best friend and fellow talk show host Gayle King, tried to quietly slip into the rally.
She walked up to the set of bleachers behind the stage and asked some women if she could scoot in.
Within seconds cameras were clicking and fans were yelling. King spent the speech in the first row of bleachers chatting up supporters, listening and and mingling with fans.
Winfrey's campaign appearance comes less than one month before the Iowa caucuses.
After Iowa, the three-state "Oprah-bama" tour moves on to South Carolina and New Hampshire on Sunday.
The nod by the empress of daytime television comes at a time when independent politicos and campaign aides believe the Democratic senator from Illinois is picking up steam. The latest Des Moines Register poll puts Obama ahead of Sen. Hillary Clinton, D-New York, in Iowa and shows him gaining ground among women.
Women are proving to be a crucial voting block in 2008 for all the Democratic hopefuls, but most especially Clinton. At a recent Obama rally in Iowa City, many women expressed the difficulty they had in deciding whether to vote for him or for Clinton because she could be a first for their gender. Watch how Winfrey's campaigning could give Obama a boost »
Winfrey's endorsement is an obvious boost for Obama in his effort to steal women voters from Clinton.
"I think it's going to help him with the women my age because she's very popular, very respected among my age group," said Linda Peterson, a middle aged mother and probable Obama voter from North Liberty, Iowa.
According to The New York Times, women make up 75 percent of the audience for the "Oprah Winfrey Show" and more than half are over 50. More than 40 percent make less than $40,000 and a quarter have no more than a high school education.
"One of the secretaries was just so excited about the fact that Oprah was coming," said Jodi Plumert, a University of Iowa professor and ardent Obama supporter. "She said 'Who would've thought Oprah, coming to little old Iowa!'"
"I think that having Oprah here on Saturday will definitely pull women out," said Iowa City resident and Obama precinct captain Cheryl Carter. "I think it will just show that women in Iowa are Barack Obama supporters."
Although Clinton will be campaigning in Iowa on Friday and Saturday, rival campaigns acknowledge Winfrey will leave little air in the Hawkeye State. Watch what issues are important to Iowans »
"Sen. Clinton is a big fan [of Winfrey's] and thinks it's great for every candidate to bring in surrogates," said a Clinton aide. "But ultimately the voters of Iowa, New Hampshire, South Carolina and America are going to vote based on the actual candidate's experience, strength, record and the ability to do the job on Day One."
The Clinton campaign will put its star on stage the day before Oprah-bama hits South Carolina when former President Bill Clinton makes campaign stops in Charleston on Saturday. Check out some other celebrities who are endorsing candidates »
Bill Clinton said Friday that his trip is "totally coincidental."
Also Saturday, the couple's daughter, Chelsea Clinton, made her first appearance on her mother's campaign trail along with the senator's mother, Dorothy Rodham -- comprising three generations of Clinton women. E-mail to a friend