But it seems they just can't help themselves.
With the election in just four days - a period when campaign professionals advise office-seekers to drop attacks and send voters to the polls with a positive message - the state's most competitive race is ending pretty much as it began: With the candidates tearing into each other.
Harris, a Republican state senator from Baltimore County who has cast Kratovil in recent advertisements as a "Martin O'Malley, tax-and-spend liberal," has opened a new line of attack this week: questioning the Democrat's handling of a pair of cases as the state's attorney in Queen Anne's County.
"We're going to continue to look at Kratovil and what makes him different," Harris campaign manager Chris Meekins said. "People need to know what his real record is."
Kratovil, who paints Harris as an extremist who will say anything to get elected, is airing a television spot pointing to newspaper articles that call his rival's claims "inaccurate," "knowingly deceptive" and "deceitful."
"We're going to push Andy Harris very, very hard on the way that he's been running his campaign," Kratovil spokesman Kevin Lawlor said. "We really think that people deserve an explanation."
The continuing negative tone of the contest reflects the stakes for both sides in the race for the seat now held by Republican Rep. Wayne T. Gilchrest. The GOP wants to retain a district that at the start of the race seemed to be an easy Republican hold. Democrats see a rare opportunity to pick up their seventh out of the state's eight House seats.
The rancor between the campaigns has been aided by outsiders. The Democratic Congressional Campaign Committee, which is planning to spend more than $1 million in the district, has produced television spots contending that Harris is beholden to the banking, insurance and energy interests that have donated to his campaign.
The anti-tax Club for Growth, which helped to bankroll the conservative Harris to victory over the moderate Gilchrest in a bitterly fought Republican primary, is airing ads labeling Kratovil "extremely liberal."
All of this has contributed to the most competitive race the 1st Congressional District has seen in decades, and one of the most expensive ever in Maryland.
"It's been a long, long time since we've had this kind of advertising," said Harry Basehart, a professor emeritus of political science at Salisbury University, who goes back more than 30 years in the district. "We haven't had anything like this in my memory."
Between attacks, the candidates are making efforts to reach across party lines. Democrats hold a slight edge in voter registration in the district, but it has voted overwhelmingly for Republican candidates in national and state elections.
New Harris advertisements feature former Gov. Robert L. Ehrlich Jr., a Republican who took 67 percent of the district vote in 2006, appealing to his "Democrat and independent friends" to support Harris. Several Kratovil spots have featured the endorsement of Gilchrest, who garnered 69 percent of the vote in 2006.
But the attacks continue to set the tone for the race. In a news release Wednesday, the Harris campaign asked why Kratovil opted against prosecuting 15 of 17 counts against a man charged with child sexual offenses, or 12 of 14 counts against a woman accused of burglary. The campaign suggested the decisions related to contributions from defense lawyers.
"Voters deserve to know why Frank Kratovil has taken thousands of dollars in campaign contributions from criminal defense attorneys with cases in Queen Anne's County," said Meekins, the Harris campaign manager, who asked: "If we can't trust Kratovil to ... enforce our laws, how can we trust him to make them?"
Lawlor, the Kratovil spokesman, said the Harris campaign was telling only part of the story. In the case of the accused sex offender, Lawlor said, Kratovil was able to get convictions on two counts that sent the man to prison for 18 months and required him to register as a sex offender. Prosecutors in a neighboring county were unable to get convictions on any of the counts, Lawlor said.
In the case of the burglar, Lawlor said, Kratovil won convictions on two counts that sent her to prison for 18 months while getting her to testify against an accomplice wanted for additional crimes who now is serving 50 years.
The Kratovil campaign was preparing a letter signed by Maryland state's attorneys praising Kratovil's work as a prosecutor.