WASHINGTON -- In an all-out broadside against the current state of campaign finance, Sens. John McCain (R-Ariz.) and Sheldon Whitehouse (D-R.I.) submitted a brief on Friday morning urging the U.S. Supreme Court to let stand Montana's century-old ban on corporate money in political campaigns despite the court's Citizens United ruling two years ago declaring unconstitutional a similar federal law sponsored by McCain.

They also took aim at the influence of super PACs, pointing to the Republican-leaning Crossroads GPS, the pro-Obama Priorities USA Action and the Tea Party's FreedomWorks.

In late December, the Montana Supreme Court had upheld the state's Corrupt Practices Act, which says that a "corporation may not make ... an expenditure in connection with a candidate or a political party that supports or opposes a candidate or a political party." The court found, by a 5-2 vote, that Montana's history of political corruption at the hands of corporate interests -- namely its Gilded Age-era "Copper Kings" -- justified the ban, which was passed by referendum in 1912 by voters who had lost faith in the state's political process.

The plaintiffs in the current lawsuit are led by American Tradition Partnership, a conservative interest group dedicated to fighting "the radical environmentalist agenda." They have asked the U.S. Supreme Court to block the state decision, arguing that it conflicts with the Citizens United ruling's declaration that corporations' independent political expenditures do not give rise to corruption or the appearance of corruption and therefore are fully protected speech under the First Amendment. The U.S. Supreme Court temporarily blocked the Montana decision in February and requested formal briefing to give the case a fuller airing.

Justice Ruth Bader Ginsburg, writing for herself and Justice Stephen Breyer, issued a statement accompanying that February order welcoming this sequel to Citizens United. "Montana's experience, and experience elsewhere since this Court's decision in Citizens United ... make it exceedingly difficult to maintain that independent expenditures by corporations 'do not give rise to corruption or the appearance of corruption,'" Ginsburg wrote. A full Supreme Court hearing "will give the court an opportunity to consider whether, in light of the huge sums currently deployed to buy candidates' allegiance, Citizens United should continue to hold sway."

In its formal petition to the Supreme Court, American Tradition Partnership dismissed Montana's fact-bound decision and Ginsburg's nod to the country's post-Citizens United experience.

"The facts are irrelevant," the petition argued. "The core holding of Citizens United ... is that the independence of independent expenditures means that they pose no cognizable quid-pro-quo-corruption risk and no other cognizable governmental interest justifies banning corporate independent expenditures."

McCain and Whitehouse strongly disagree in their brief. Siding with Montana and agreeing with Ginsburg and Breyer, the senators ask the Supreme Court "to confirm that Congress and state legislators may, upon an appropriate record demonstrating the potential for corruption or perceived corruption created by independent expenditures, enact legislation in response to that real and significant threat." McCain, a notable supporter of Mitt Romney in the Republican primary race, has not been shy during this campaign season about emphasizing the differences between himself and the presumptive GOP nominee on Citizens United and super PACs.

Represented by former Acting Solicitor General Neal Katyal, now in private practice and a professor at Georgetown Law, the senators suggest that the justices simply deny American Tradition Partnership's petition, which would leave the Montana Supreme Court's decision upholding the state law in place. If they grant the petition, the senators urge the justices to conduct full briefing and oral argument -- rather than issue a summary reversal -- to "confirm lawmakers' continuing authority to respond when the evidence shows 'that a problem exists,'" to quote from Justice Anthony Kennedy's majority opinion in Citizens United.

"And a problem does exist," the brief continues. "Evidence from the 2010 and 2012 electoral cycles has demonstrated that so-

called independent expenditures create a strong potential for corruption and the perception thereof. The news confirms, daily, that existing campaign finance rules purporting to provide for 'independence' and 'disclosure' in fact provide neither. Regulatory filings show that much of the funding for independent expenditures comes from shell companies, pass-through entities, and non-profit organizations that conceal the true source of the individuals and companies supporting them."

The justices may soon have an opportunity to speak specifically to that last consideration. In a separate case, a federal appeals court on Monday refused to block an April decision by a district court judge closing the loophole that had allowed certain nonprofits, such as Karl Rove's Crossroads GPS, to spend unlimited sums without disclosing their donors.

Meanwhile, Senate Minority Leader Mitch McConnell (R-Ky.), a longtime foe of campaign finance restrictions, submitted a brief in late April supporting American Tradition Partnership and contesting the claim that unlimited corporate money has played any outsized role since Citizens United. "A review of FEC records for independent expenditure-only committees -- i.e. the so-called Super PACs -- supporting the eight leading Republican Presidential candidates has evidenced minimal corporate involvement in the 2012 election cycle," he wrote.

McCain and Whitehouse's argument takes aim at the broader message of Citizens United, as interpreted by American Tradition Partnership and the Montana Supreme Court's dissenters -- that unlimited independent expenditures, whether from a corporation or an individual, have no corrupting effect on politicians and the political system. It "cannot be so," they argue, that this is a blanket ruling of law impervious to facts showing otherwise. As evidence, the senators cite candidate-specific super PACs that have staff and consultants closely connected to the campaigns (a footnote mentions that the main pro-Obama super PAC is run by the president's former deputy press secretary while the leading pro-Romney super PAC was founded by the general counsel of Romney's 2008 presidential campaign) as well as "coordinated" fundraising and advertising activities. The senators argue that such groups engage in "identity-laundering" thanks to deficient disclosure rules.

In the end, the senators say, the appearance of corruption is in the eyes of the people, not the justices, and polls find opposition to Citizens United and diminished faith in the electoral process. Although "[p]oll results should not direct Court decisions ... these results show that the Court’s assessment of perceived corruption was at odds with the perception held by most Americans," the brief states.

Montana Attorney General Steve Bullock's brief opposing American Tradition Partnership's petition is expected to be filed by the end of Friday. The justices will likely discuss whether to take the case in a private conference later this summer.

