The Bloomberg and Ferrer campaigns are waging a daily war against each other as Election Day nears, employing one of the oldest tricks in the political playbook – opposition research – with a few modern twists.

From “trackers,” the staffers the mayoral campaigns are sending to spy on their opposition, to “push back” – the research-filled messages spokesmen send to dispute enemy claims – to unprompted e-mails chock full of juicy bits of hypocrisy, this mayoral campaign season is rife with signs of opposition research.

When asked about opposition research, both campaigns say they are not collecting information with the intent of “going negative.”

“We’re not going to be backstabbing. We’ll stab you right in the front,” Mayor Bloomberg’s senior campaign adviser, William Cunningham, said. “Trust me, they’ll know when I’m coming for them. They won’t have to guess. Here’s the point. We will, when there’s hypocrisy, we’ll point to it. When there’s a distortion, we’ll point to it. When there’s an outright distortion of facts, we’ll point to it. They won’t have to wonder where it’s coming from.”

Ferrer sources likewise say they only use their Bloomberg research to point out inconsistencies in his statements.

According to authorities in the art of opposition research, lashing out at one’s rivals might not be the ideal goal of research. Instead, the aim should be using information strategically to establish a pattern that can damage the opponent while at the same time anticipating and defending against attacks on your own candidate.

“Individual charges rarely damage a candidate,” Daniel Shea, the author of “Campaign Craft,” said. “It’s not one accusation or even two or three. Candidates are damaged by a pattern that can be developed.”

Mr. Shea, a professor of political science at Allegheny College, added, “Charges made too early might have a damaging impact but fade. A charge coming too late won’t make a difference.” The Ferrer and Bloomberg campaigns both say they conduct opposition research by compiling easily available, but sometimes unknown, public information.

Mr. Cunningham said the most important resource the campaign has is a Web site many people use daily.

“It’s called Google,” he said. “I can Google up a lot of what he’s said or done.”

He said the campaign also sifts through years’ worth of Ferrer biographies and campaign mailings. “It’s all publicly available knowledge. It’s not hard to find,” he explained. “You know, you take a statement of fact and you look at it. If he says I went to such and such school, if it doesn’t match, then you ask why.”

Mr. Cunningham said the Bloomberg campaign has a “team of truth” making sure that no one distorts the mayor’s record.

An authority in opposition research, Philip Howard, whose book “New Media Campaigns and the Managed Citizen” will be out this week, said the first phase of a modern campaign involves going online and “Googling” the opponent. Then, he said, researchers move to databases like LexisNexis to search for information. They also load campaign mailings, speeches, television appearances, advertisements, and documents like voting and property records into a computerized database.

“Once you’ve got megabytes and megabytes, the team sifts through for conflicts,” Mr. Howard, a professor of political communication at the University of Washington, said.

He said computers have changed opposition research.

“It used to be that opposition research had more to do with personal dirt,” he said. “You had to rely on stories. It was tough to verify. You were essentially hiring private detectives. Today it’s data driven.”

The Ferrer campaign says the Bloomberg campaign has been far more aggressive than it has been on the opposition research front. The Ferrer campaign’s spokeswoman, Jen Bluestein, points to Mr. Bloomberg’s campaign spokesman, Stuart Loeser, as the root of what she sees as a culture of “trash-talking” at camp Bloomberg.

Mr. Loeser, who was the research director for Mark Green’s 2001 mayoral campaign, came to the Bloomberg campaign equipped with an arsenal of knowledge about Mr. Ferrer, and isn’t shy about letting reporters know about it.

Thirty-four minutes after the candidates concluded their final statements in last Thursday’s debate, Mr. Loeser sent an e-mail to reporters, headlined “Ferrer is wrong on his resume AGAIN, flip-flops on the death penalty AGAIN, and hypocritically called himself a reformer. “The message used newspaper and television sources to refute three of Mr. Ferrer’s statements during the debate, in which Mr. Bloomberg did not participate.

Perhaps the most successful use of Bloomberg research so far occurred last month, when his campaign sent an e-mail to reporters headlined “FERRER: WRONG ON HIS OWN RESUME,” which disclosed an entry on Mr. Ferrer’s blog that said he attended public schools when he actually attended only Catholic and private schools. The news, which came the day Mr. Ferrer was scheduled to campaign at a school with the chairman of the Democratic National Committee, Howard Dean, ended up on the front page of three newspapers the next day.

Ms. Bluestein said, “Since the Bloomberg campaign spokesperson’s previous job was to try to compile dirt on Freddy Ferrer, it’s pretty clear that the Bloomberg campaign values trash talking and smearing more than putting forward positive plans for the city.”

She added, “That’s okay, it’s their choice – we consider ‘Bloomberg Tracker 1 and 2’ a permanent part of our traveling team.”

Ms. Bluestein was referring to the Bloomberg campaign “trackers” who go to Mr. Ferrer’s events with tape recorders to report back on what he says.

The Ferrer campaign also has a tracker who attends and records Bloomberg events, except when Bloomberg staffers do not allow him inside. The Ferrer tracker sometimes even distributes handouts, providing instant responses to what the mayor is announcing.

Mr. Loeser countered that with 32,000 volunteers, it’s not hard to find people to attend Mr. Ferrer’s events. More generally, he said the Bloomberg campaign isn’t out to smear. It just wants to let voters know when Mr. Ferrer misrepresents his record.

“When it comes to Freddy Ferrer, the truth hurts,” he said.

The Ferrer campaign has made its own uses of research. The day after Mr. Ferrer appeared with Dr. Dean, the Ferrer campaign sent out two unprompted e-mails attacking Mr. Bloomberg’s record, one titled, “REAL FISHY: BLOOMBERG TAKES CREDIT FOR GIULIANI-FERRER PROJECT,” and another called “BLOOMBERG: WRONG FOR STATEN ISLAND,” containing a list of crime numbers that were up on Staten Island, where crime overall has dropped during the Bloomberg years.

The Democratic State Committee provides backup to the Ferrer campaign with its own information campaign. It has informed reporters, for example, how much the mayor has donated to Republican causes.

So far, the Bloomberg team appears to be winning the opposition research war.

“There are a lot more stories that are sticking on Freddy,” said a longtime political consultant, Joseph Mercurio, who worked for a Ferrer opponent, C. Virginia Fields, in the Democratic primary.

Democrats say Mr. Bloomberg has an advantage in this arena because he is a billionaire financing his own campaign.

The experts, however, say this might be one area where money can’t buy success. “It is one area where dedicated staffers can help level the playing field a bit,” Mr. Shea said. “Volunteers and eager activists can’t help balance out disproportional television buys, but they can roll up their sleeves and find everything that Bloomberg has ever said or ever written.”