INDIANAPOLIS -- Tickets for Saturday's town hall meeting featuring presidential candidate Sen. Barack Obama at Plainfield High School were snatched up less than 90 minutes after details of the visit were announced Thursday.

Obama's campaign said doors will open at 12:30 p.m., and a speech is scheduled for about 2:20 p.m. in the gymnasium of the high school west of Indianapolis.

The visit will come weeks before Indiana's May 6 primary, which could help decide who grabs the Democratic Party's nomination.

Obama and fellow Democratic candidate Sen. Hillary Rodham Clinton are beginning to take interest in Indiana's 72 delegates because they are locked in a tight race. 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.

"We've had unbelievable excitement for several months. Now that we know ... the Indiana primary is going to matter in the presidential primary ... people are out of their minds excited. I think it's really great to see," said Kip Tew, chairman of Obama's campaign in Indiana.

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.

"If you look at what the national prognosticators are saying, they're saying that Indiana is probably one of the last few remaining swing states in this contest," said the state's Democratic Party chairman, Dan Parker. "So (Obama's visit) doesn't shock me."

Parker said he hopes both candidates would visit the state many times.

Joe Hogsett, a Clinton campaign coordinator in Indiana, said Obama's visit is "indicative of the fact that both Sen. Clinton and Sen. Obama are going to pay a lot of attention to Indiana and that Hoosier voters are going to have an opportunity to help pick a president."

While Clinton has not yet scheduled a trip to the state, his campaign said she plans to be in Indiana early and often.

With an important Pennsylvania contest six weeks away, Obama is playing down his chances there, even though a victory would effectively finish Clinton. His aides are emphasizing instead the need to campaign in Indiana, North Carolina and other presumably friendlier states that will vote after Pennsylvania.

The Obama campaign expects Indiana to be a battleground because of its large black population and the fact that the northern part of the state is in the Chicago media market, where the Illinois senator is often on TV and in the news. But Indiana also has a significant blue-collar population and Evan Bayh, the state's senator and former governor, will actively campaign for Clinton.

Clinton, a U.S. senator from New York, is banking heavily on Pennsylvania. A solid win here could sustain her claim to late-season momentum and the ability to win big, industrial states.

Obama's last trip to Indianapolis was for a private fundraiser in July 2007.