As more outside third-party money enters the race for Hawaii’s 1st Congressional District, Republican Charles Djou has renewed his call for his opponent, Democrat Mark Takai, to sign a clean-elections pledge that would seek to have each side donate matching funds to charity.

With polls showing a dead heat, outside groups are doing what they can financially to bring their candidate over the finish line.

"I’ve always said consistently these outside third-party ads are unhealthy for our democracy," Djou said.

Takai also denounced the spending.

"I don’t think outside money is helpful," he said. "But the fact is, it’s legal."

This week, American Action Network, a conservative political action committee headed by former Republican U.S. Sen. Norm Coleman of Minnesota, spent the first $21,000 of a planned $300,000 television ad buy against Takai.

Meanwhile, the group Working Families for Hawaii, a labor group financed by the American Federation of State, County and Municipal Employees, entered the race with $144,000 in TV ads against Djou. VoteVets.org, a group that supports progressive veterans of the wars in Iraq and Afghanistan for Congress, already supported Takai with $185,000 in early October, on top of $175,000 it spent to raise his name identification in the primary.

The ads represent independent expenditures by so-called super PACs, which by law are allowed to spend an unlimited amount to advocate election or defeat "of a clearly identified candidate" as long as there are no direct candidate contributions and there is no coordination between the super PAC and any candidate or party.

The ads are often negative and stretch the truth, said Carmille Lim, executive director of public advocacy group Common Cause Hawaii.

"A lot of times, independent expenditure groups are really trying to sway public opinion with misinformation and disinformation," she said. "So when a candidate approves a message, that has a different type of weight and it’s easier for us to hold our elected officials accountable versus when another group is saying something and then the candidate would be held more accountable to them."

Independent expenditures exploded in 2010 following the landmark Supreme Court decision known as Citizens United, which said super PACs can accept unlimited contributions from corporate and union treasuries as well as from individuals.

That prompted the use of the Common Cause People’s Pledge. In the 2012 U.S. Senate race between Scott Brown and Elizabeth Warren in Massachusetts, both candidates signed an agreement that bound them to make a contribution to a charity equal to 50 percent of the amount of outside advertising that came in on their behalf.

Since then, Common Cause has attempted to duplicate the pledge in other states. In 2014, only the candidates in the Rhode Island gubernatorial race have agreed.

Djou has said he supports the pledge and called on Takai to do the same. The Takai campaign has not responded.

"I’m willing to go forward with it. Mark Takai is not," Djou said, adding that the state Democratic Party has supported similar positions in the past. "I am hopeful that the Democratic Party of Hawaii will join my campaign to put pressure on Mark Takai for clean elections."

Lim said Common Cause has received no word that the Takai camp is willing to negotiate a pledge agreement.

Alex Hetherington, a spokesman for Takai’s campaign, applauded the effort, and said Takai’s record on clean elections speaks for itself.

"Mark has always been in favor of comprehensive campaign spending reform, and has voted in favor of it during his time in the Hawaii state Legislature," Hetherington said. "It is ironic that Charles Djou claims he would sign the Common Cause pledge as he has voted against campaign spending reform during his time in Congress."

The Democratic Party of Hawaii denounced the American Action Network, tying it to tea party Republicans and other conservative super PACs such as Karl Rove’s American Crossroads GPS.

"Clearly, Djou’s special interest allies know that he cannot stand on his own record," Carolyn Tanaka, a spokeswoman for the Hawaii Democrats’ coordinated campaign, said in a statement. "This is Djou’s fourth time trying to pull the wool over our eyes and now it is not surprising that his allies are swooping in to distract from the real choice in this election: a choice for a progressive like Mark Takai or a tea party Republican like Charles Djou."

Djou made a similar denouncement of the Working Families for Hawaii ad, saying state Democrats should urge third-party groups to take down such negative ads.

"If Mark Takai steps up, and the Democratic Party pushes him to do the right thing, I’ll match it," Djou said, referring to the Common Cause pledge. "I think if the clean elections pledge were in place you wouldn’t see as many of these dirty, negative attack ads from third-party groups."