It’s not surprising that House Republicans and Democrats both threw earmark reform plans into the mix the same day President Barack Obama announced his own plan. Earmarks are second only to lobbyists as Congressional whipping boys these days. But, when it comes to Congressional earmarks, neither political party has clean hands.

Amid the partisan posturing and point-scoring during the earmark debate, a genuinely good idea emerged in the form of a call to investigate the relationship between earmarks and campaign contributions. The relationship is a particularly insidious one in an era of spiraling campaign costs.

The various reform proposals introduced recently contained no real surprises. There was agreement on the need for more timely transparency. Some call for a reduction in the number of earmarks, and others want to make sure that earmarks in both authorizing and appropriating legislation are covered. But none will end the debate as to whether earmarks are inherently good or bad, whether they are Congress’ constitutionally mandated power of the purse or wasteful pork-barrel spending. There is also the simple yet daunting problem that even an earmark denounced in 49 states usually results in a self-congratulatory press release in the district where the money is headed.

While much of Arizona GOP Rep. Jeff Flake’s most recent attack on earmarking was timed to serve partisan purposes, his proposed investigation is one that opponents as well as proponents of earmarking should endorse. His amendment called for an ethics committee investigation into the intersection of campaign contributions and earmarks. The amendment came shortly after media reports identified a single appropriations bill in 2008 in which 104 Representatives secured earmarks totaling nearly $300 million for the clients of a single lobbying firm. The PMA Group, through its employees and political action committee, had made campaign contributions totaling more than $1.8 million since 2001 to the Members who took credit for those earmarks benefiting PMA clients.

While the sheer size, scope and audacity of its earmark pursuit makes the PMA Group a poster child for the need for earmark reform, what the PMA example reveals most clearly is the potentially corrupting link between campaign contributions and earmarks. Even the most ardent earmarkers should want to avoid the appearance of such a pay-to-play system.

Flake was on the right track in calling for an investigation of this corrupting relationship. His subsequent proposal to scale back an investigation to focus solely on PMA was far more partisan than practical. An ethics inquiry in both the House and Senate into the overarching nexus between earmarks and campaign contributions should be the starting point of any effort to reform the earmark process.

The inquiry should recommend what rules or laws should be implemented to assure the American people that earmarks are not being exchanged for campaign contributions. Should each Member requesting an earmark be required to disclose any campaign contributions from the beneficiary? From the lobbyist or bundler acting on behalf of the beneficiary? Or should a Member be prohibited from requesting an earmark on behalf of a campaign contributor? These are the kind of questions such an inquiry should examine. And because this is a bipartisan problem, any action or vote on this matter should not fall along party lines. It is simply not enough to deny any relationship between earmarks and campaign contributions. That denial rings hollow.

Even if an investigation finds no outright corruption, the pervasive appearance of corruption is damaging to Congress. Public concern over the appearance of corruption will continue as long as federal candidates are forced by the current system to go hat-in-hand to large contributors and to rely on bundlers.

With expected improvements in transparency, scrutiny of earmarks will only increase. An investigation of earmarks and campaign contributions will lead to new discussions about the way campaigns are financed and about ways to provide new incentives for small donors to give and candidates to pursue these funds. Breaking the link between campaign contributions and earmarks would be a good start. When that happens, it will be interesting to see how many of these earmarks just disappear.

Meredith McGehee is policy director of the Campaign Legal Center and also heads McGehee Strategies, a public-interest consulting business.