It has been two years since the Supreme Court issued its decision in the case Citizens United v. Federal Election Commission, and we are only now just beginning to see how its overturning of a century of campaign finance law is distorting the electoral process. Rather than acting truly independently of campaigns, as the majority of justices envisioned, these entities exclusively act on behalf of individual candidates — and are typically run by former aides. Rather than encouraging the universal right of free speech, the ruling has had the effect of providing a megaphone for the rich to drown out all other voices.

That's what's happening in South Carolina, where a barrage of attack ads from a super PAC supporting Newt Gingrich — and largely bankrolled by one wealthy supporter — has brought the former House speaker within striking distance of an upset against front-runner Mitt Romney in today's primary. It's a mirror image of what happened in Iowa, where a Romney super PAC hobbled Mr. Gingrich's chances, and it's likely a mere prelude to what will happen as the race moves next to Florida.

In Annapolis this week, activists rallied as part of a nationwide effort to reverse this tide of unaccountable special-interest money in politics. They are asking state and local officials, including Maryland's General Assembly, to pass resolutions calling for an amendment to the U.S. Constitution to, effectively, overrule the Supreme Court. The proposal attacks two key elements of the Citizens United decision: that corporations have the same free speech rights as individuals and that money in an electoral campaign is equivalent to speech.

It is a worthy effort, but in the near term it stands little chance of success. Constitutional amendments must first be approved by a two-thirds vote in both houses of Congress before being sent to state legislatures for ratification, and at the moment that appears a near impossibility. Although the corrosive influence of money on politics should be clear to Democrats and Republicans alike — after all, now both GOP-leaning corporations and Democrat-leaning unions see their power to influence voters unchecked — the reaction to Citizens United has fallen largely on party lines, with Democrats pushing for reform and Republicans resisting.

Given how the 2010 congressional elections played out, that may not be so surprising. According to the website opensecrets.org, outside spending by liberal groups had typically outstripped that by conservative groups in recent elections. But that flipped in 2010. Behind huge efforts by groups like the U.S. Chamber of Commerce, the American Action Network and Karl Rove's Crossroads GPS, conservative groups spent twice as much as liberal ones in that year. Republicans regained control of the House of Representatives and picked up seats in the Senate, as well as hundreds of seats in state legislatures.

But the effects of Citizens United on our electoral system are still evolving. The story of 2010 was outside groups pushing slates of like-minded candidates across the nation. So far in 2012, it's the rise of super PACs and their impact on the Republican presidential primary. Although the candidates are not allowed to coordinate the activities of these groups, they have served as powerful weapons on the candidates' behalf. Mr. Romney didn't need to direct a super PAC supporting him to go after Mr. Gingrich when the former House speaker's poll numbers rose in Iowa, and Mr. Gingrich didn't need to tell the Winning our Future PAC to go after Mr. Romney in South Carolina.

As things have played out there, the supposed independence of the super PACs has actually worked in the candidates' favor rather than against them. Mr. Gingrich has disavowed many of the attacks in a super PAC-funded, Michael Moore-style video polemic against Mr. Romney's activities at his former investment firm, Bain Capital — and has urged Mr. Romney to do the same about attacks from his own super PAC allies. But the documentary, "When Mitt Romney Came to Town," is still up on the group's website, and Winning our Future has just bought another $1.8 million of airtime in South Carolina for new attacks, largely thanks to a $5 million check from a Nevada casino magnate who has long supported Mr. Gingrich.

Republicans so far have seen the super PACs and other consequences of Citizens United as a positive, but they might change their minds if a few seven-figure checks help keep an anti-Romney (be it Mr. Gingrich or someone else) in the race for weeks or months to bludgeon the eventual nominee. They may look less appealing yet when we hear from those that support President Barack Obama (and one exists, despite his publicly stated opposition to super PACs). What's going on in South Carolina is doing little to help voters make good, fact-based decisions in advance of today's primary. But the ugliness there may be the price we have to pay for developing a national consensus in favor of campaign finance reform.