PLAINFIELD, Ind. -- Sen. Barack Obama told hundreds in a campaign event in Plainfield on Saturday that "the forces of division" are using race to try to split Americans during the Democratic presidential nomination contest.

"We have to come together," Obama said at a town-hall-style meeting at Plainfield High School.

Obama cited inflammatory remarks made by his pastor that are now being used as political ammunition against him -- remarks that Obama has denounced.

"If all I knew were those statements I saw on television, I would be shocked," Obama said.

Obama suggested that more and more is being made of racial divisions as his contest with Sen. Hillary Rodham Clinton heats up.

"I noticed over the last several weeks that the forces of division have started to raise their ugly heads again. And I'm not here to cast blame or point fingers because everybody, you know, senses that there's been this shift," Obama said.

"It reminds me: We've got a tragic history when it comes to race in this country. We've got a lot of pent-up anger and bitterness and misunderstanding. ... This country wants to move beyond these kinds of things."

The Illinois senator's comments came a day after he denounced statements in videos appearing on television and on the Internet of sermons by the Rev. Jeremiah Wright, pastor of the Chicago church Obama joined nearly 20 years ago.

"Most recently, you heard some statements from my former pastor that were incendiary and that I completely reject, although I knew him and know him as somebody in my church who talked to me about Jesus and family and friendships."

Obama said that pointing out racial differences only makes it harder to "deliver on the big issues we face in this country," which he said include health care, the slumping economy, terrorism and caring better for veterans.

Obama, whose mother's family was from Kansas and his father from Kenya, said he was speaking "as someone who has little pieces of America all in me."

He said schools should do a better job of teaching all students African-American history "because that's part of American history," as well as women's struggle for equality, the history of unions, the role of Hispanics in U.S. and other matters that he suggested aren't given enough attention.

"I want us to have a broad-based history" taught in schools, he said, even including more on "the Holocaust as well as other issues of oppression" around the world.

During a 45-minute question and answer session, Obama addressed some issues specific to Indiana, including the viability of ethanol as a fuel alternative.

"It's a good transitional technology to start developing the infrastructure, the truth of the matter is that corn-based ethanol is not as efficient as ... what the Brazilians are doing with sugar cane, which means that we have to find new ways of creating the energy that we need for economic growth and our quality of life," Obama said.

Obama spoke in the gymnasium of Plainfield High School, near Indianapolis, as he directed his political attention at states beyond the critical April 22 Pennsylvania primary.

"We are going to be campaigning actively in Indiana," Obama said to cheers. Indiana and North Carolina have primaries on May 6, two weeks after Pennsylvania.

Tickets for Saturday's appearance by Obama, D-Ill., were snatched up less than 90 minutes after they were made available Thursday.

Obama's event came five days before Clinton is scheduled to make campaign stops in Indiana. Details of Clinton's plans for Thursday have not yet been made public, though her Indiana campaign coordinator said she would visit several Indiana communities.

Obama and Clinton, D-N.Y., are beginning to take interest in Indiana's May 6 primary and the state's 72 delegates because the candidates still are locked in a tight race two months after this year's Democratic primaries began.

Because many states hold primaries before May, presidential nominations often are wrapped up before Hoosiers get to vote. But because of this year's tight race, this is the first time in 40 years that Indiana's Democratic presidential primary has had the opportunity to matter.

According to an Associated Press count, Obama has 1,598 delegates, including separately chosen party and elected officials known as superdelegates. Clinton has 1,487, according to the AP. It takes 2,025 delegates to secure the Democratic nomination for president.