They differ, however, on what a clean campaign should be.
The five candidates who will face off in the August 14 primary are:
-- Dennis Hall, a security consultant living in Cambridge. He's a Janesville native and former member of the Janesville City Council.
-- Mark Pocan, a Madison Assembly representative.
-- Kelda Helen Roys, a Madison Assembly representative.
-- Matt Silverman, a lawyer and a captain in the Army Reserves who lives in Madison.
-- Dave Worzala, Dane County treasurer.
Pocan began the clean campaign discussion April 24 with a press release urging his primary opponents to sign his clean campaign pledge. The pledge read, in part:
"I will not mention the name of my opponents in any paid communications in a negative way by my campaign committee unless I am attacked by name."
Pocan said he offered the clean campaign pledge as part of a united effort to elect U.S. Rep. Tammy Baldwin to the U.S. Senate and re-elect President Barack Obama.
"This campaign is about bringing progressive leadership to Washington in challenging times," Pocan said. "That's what voters deserve to hear, not attacks."
The five Democrats are running for a seat opened when Baldwin said she would step down to run for the Senate.
Two days after Pocan issued his pledge, Worzala countered with a pledge that included monetary penalties for those violating the pledge. His pledge reads, in part:
"For any paid communication attacks paid for by the campaign or supporting third parties, I agree that the guilty campaign will pay 50 percent of the cost of airing or disseminating TV, radio, mail or online advertising to the charity of the targeted opponent's choice."
Worzala said his plan has been proven successful in the U.S. Senate race in Massachusetts between Democrat Elizabeth Warren and Republican Scott Brown.
Roys responded with a call for a ban on corporate political action committee contributions.
"Four out of the five candidates in the 2nd District primary have joined Kelda's pledge to reject corporate PAC money," Roys said in a May 2 press release. "Rep. Mark Pocan stands alone as the only candidate in the 2nd District race accepting corporate PAC contributions."
When asked to respond, Pocan said he hoped all candidates would recognize that their values were not well served by attacking each other. He "applauded" Worzala for agreeing to a clean campaign and said he hoped all the candidates would do the same.
Hall and Silverman said they plan to run clean campaigns.
"I just can't imagine a reason why we would not want to run clean campaigns," said Hall. "Just look at what the Republican presidential candidates have done to each other. We don't want to emulate that."
Silverman said his concern is for the voters.
"I don't believe it's our job to tell other candidates how to run their campaigns," he said. "I will run a clean campaign. The voters will decide how well we do that."