Among the most iconic moments of the 2008 presidential campaign were the scenes of Barack Obama, shirtsleeves rolled up, in front of a sea of voters that seemed to go on forever.

Even toward the end of the election season, the crowds dwarfed those of his Republican opponent, Senator John McCain of Arizona. At some locations, tens of thousands of Democrats rallied for their candidate.

Since becoming president, Mr. Obama has gone small. Except for a few rallies during the height of the health care debate, the president has largely eschewed stadiums and wide open spaces in favor of smaller town-hall-style meetings or even backyard conversations.

But that is about to change.

On Tuesday, the president is scheduled to hold an old-fashioned campaign rally on the campus of the University of Wisconsin, Madison. Party officials said they expected thousands to cram onto Library Mall, an outside setting, to see Mr. Obama.

A senior Democratic Party strategist said the event would be the biggest political rally since the end of the campaign and is meant to recapture “some of the old excitement and energy from the 2008 campaign that was so essential to Obama’s and Democrats’ success.”

The strategist, who spoke on the condition of anonymity to discuss the thinking behind the new approach, said the White House was also trying to leverage the single event with more than 200 “watch parties” across the country, much as Mr. Obama’s campaign did two years ago.

“It’s not about one event in one state — it’s about generating excitement across the country,” the strategist said. “It’s a pretty big deal.”

For the president, it had better be. With the midterm election just over five weeks away, Mr. Obama’s Democratic Party is suffering from a lack of enthusiasm, as measured in numerous public opinion surveys.

While many of the Congressional races will turn on local issues and the performance of individual candidates, party officials are eager to try to match some of the national energy that has been generated among Republicans by the Tea Party movement.

The Madison rally will, in part, be a test of whether Mr. Obama can still provide that kind of political punch. In February 2008, Mr. Obama, then a candidate, filled the 17,000-seat Kohl Center in Madison and left thousands more outside, waiting to get in.

Officials in Madison have said the Library Mall area can hold a maximum of 15,000 people, but that counts space likely to be taken up by the stage, risers and barricades. Democratic National Committee officials have declined to predict how many will show up.

Tim Kaine, the committee chairman, announced last week that Ben Harper, a blues and folk singer, would help headline the event.

“Kicking off our Moving America Forward events with a college and youth focus in Madison will create momentum as we head into the last five weeks of this critical campaign,” Mr. Kaine said, “and having Ben Harper as part of the lineup on Tuesday is a great way to get things started.”

The president will continue to campaign in smaller, backyard settings, which Dan Pfeiffer, the White House communications director, said last week was a way for Mr. Obama to have “an intimate conversation” with voters.

And aides said they like the backyard backdrop on television.