And campaign aides to Pat O’Connor — a Chicago alderman seen as a top contender because of his strong base in the city’s 40th Ward and his close ties to Democratic Mayor Richard M. Daley — say he has accelerated his money-raising efforts in recent weeks and now is among the best-funded contenders.

Some of the candidates also are benefiting from the active backing of outside groups. Feigenholtz, for example, has been boosted by independent expenditures from the powerful political action committee associated with the Service Employees International Union as well as EMILY’s List, which supports Democratic women candidates who favor abortion rights, and also has the endorsement of the National Organization for Women.

Fritchey is endorsed by the Illinois AFL-CIO, the Teamsters Union’s Chicago affiliate and the Illinois Federation of Teachers. Geoghegan, has emerged as a darling of Internet-based liberal activist groups and has the endorsement of Progressive Democrats of America.

But even those candidates who don’t have to campaign by shoe leather alone can hardly afford not to meet and greet voters in the run-up to this closely contested primary. Unless one of the candidates figures out a way to break from the pack, this could be one of those elections in which every vote counts.

This has prompted the candidates to make their own guesses about which district residents are most likely to turn out. Older voters tend to have the highest participation rates in general, and Tom Bowen of the Quigley camp says his campaign is targeting this demographic. “In a small, low-turnout election like this, there’s an older electorate,” he said. “Since they’re home during the day, we’ll call all day. We buy TV during the day, not in prime time, which is more expensive. These voters watch ‘The View,’ not ‘Boston Legal.’”

Forys, meanwhile, who immigrated with his family from Poland when he was a child, is hoping for strong backing from the district’s sizable Polish-American community.

Reform’s the Word

Paul Green, a professor of policy studies at Chicago’s Roosevelt University and a longtime commentator on local politics, made a prediction in early December following the allegations of corruption and misconduct that prompted federal authorities to arrest Blagojevich.

“All the candidates for the Fifth District seat will call themselves pristine ‘reformer’ types, and anyone who wants to run who is not of that ilk will have a real disadvantage,” Green said. “This could be one of the first times someone with no political experience can make a run at it, and win.”

But even the current officeholders seeking the House seat are closely associating themselves with the “change” theme that was central to Obama’s victorious campaign for president.

Perhaps the easiest way for voters to cut through the confusion caused by the crowded primary field is to decide whether they believe they would be better represented by a politically experienced candidate who is familiar with navigating the corridors of power, or see a better hope for change in one of the political newcomers in the field. The Democratic candidate lineup has ample numbers of both.

History suggests that district has a tendency toward political experience that could benefit state lawmakers Feigenholtz and Fritchey; county Commissioner Mike Quigley, who has the endorsements of the city’s major daily newspapers, the Chicago Tribune and Chicago Sun-Times; and O’Connor, a veteran of Chicago’s city council.

Blagojevich, who held the seat from 1997 until his first election as governor in 2002, and Emanuel, his successor and a former aide to President Bill Clinton, were very well-connected politically when they first ran for the seat. Much of the current district was long represented by Democrat Dan Rostenkowski, who was first elected in 1958 and rose to become the influential chairman of the House Ways and Means Committee until a corruption scandal led to his defeat in the 1994 election.

Even some of the less personally known candidates have names that are familiar to those acquainted with politics on Chicago’s North Side. Cary Capparelli is a local businessman whose father, Ralph, was a state representative for 25 years. Frank Annunzio, a former Chicago Housing Authority official, is the great-nephew and namesake of a former 13-term Democratic congressman who represented some communities in the district, mainly in the western part of the district.

Alternatively, should voters choose to depart from form, they might elect one of the handful of “outsider” candidates, such as Wheelan, Geoghegan or Bryar. Wheelan has two eye-catching television spots: In one, he is speaking to the camera underwater, and in the other, he is hanging upside down, both as metaphors of sorts for the economic downturn.

Geoghegan’s trademark issue is opposing the massive federal government bailout of the nation’s financial industry, arguing that the aid should instead be directly targeted to workers and homeowners who have been negatively affected by the recession. Bryar, seeking to rally voters who want an outsider candidate, launched a Web site that mashes together parts of the names of the four elected officials who are running for the seat — www.ofritchleyholtz.com — and criticizes them as career politicians.

This insider-vs.-outsider dynamic will also provide a test of how much muscle the Chicago Democratic Party organization has in 21st century city politics. And that test may determine success or failure for O’Connor, who is Daley’s unofficial floor manager in the city council. The days of the all-powerful Democratic machine — symbolized in the memories of many Chicagoans by longtime Mayor Richard J. Daley, the late father of the current mayor — are long past. But O’Connor is strong in his own ward and he has ties to other local party officials built over a quarter-century in city politics.

“Pat O’Connor came up through the traditional Democratic organization in Chicago,” explained John Pelissero, a professor at Chicago’s Loyola University who teaches courses on local politics. “He probably expected he would be tagged for all of his decades of loyal work for the party, that they would indeed turn to him and say, ‘This is our guy.’”

O’Connor’s background established him as a top-tier contender for the nomination immediately after he entered the race. But he geared up slowly, only recently launching a fully operational Web site and hiring Phil Molfese of the consulting firm Granger Terry as a campaign manager.

Molfese said O’Connor has been reserving his resources for the campaign’s end game. “The other candidates are spending all this money telling people there’s a special election  . . .  OK, the voters know there’s going to be an election, and they’ll go vote, but who are they going to vote for?” Molfese said last week. “We haven’t spent a lot of money up until this point, so now is the time, as people make their decisions, that we’re going to start spending it, running our commercial, sending out mail, encouraging people to learn more about O’Connor.”

The Democratic field also includes Jan Donatelli, a military veteran and former commercial airline pilot, and Carlos Monteagudo, an immigrant from Cuba who is the third medical doctor in the field.

Among the six candidates competing for the Republican nomination is Tom Hanson, who lost by 74 percent to 22 percent in November as the GOP challenger in Emanuel’s last House race. Hanson, who owns a commercial real estate company, identifies himself on his campaign Web site as a “liberal Republican.”

Jon Stewart, a businessman and former professional wrestler seeking the Republican nod, also has shown recognition of the district’s Democratic bearings. The candidate, who is no relation to the TV star of Comedy Central’s “The Daily Show,” repeatedly sought to associate himself with Democrat Obama during a recent candidate forum in downtown Chicago.

Green Party voters on Tuesday will decide among five candidates.