Today, the House will begin the markup of its legislative response to the Supreme Court’s decision in the Citizens United case, which opened the door to unlimited spending by corporations and unions in federal elections.

[IMGCAP(1)]Between the Democrats that Speaker Nancy Pelosi can marshal and the Republicans who understand the urgency of knowing who is spending what in elections, there is reason for optimism for House passage of the DISCLOSE Act (Democracy Is Strengthened by Casting Light on Spending in Elections). Put together by Rep. Chris Van Hollen (D-Md.) and focusing on disclosure of the big contributors who will fund the coming torrent of attack ads now permitted by the court, the bill should pass in the House.

In the Senate, however, the path to victory for the companion measure introduced by Sen. Charles Schumer (D-N.Y.) is murkier, with opposition led by Minority Leader Mitch McConnell. However, the Kentucky Republican may have a difficult time holding together every Member of his caucus in order to bring down the bill. In fighting the proposal to disclose the money behind the ads, he will face not only public anger with the court’s ruling, which ignored decades of precedent, but he will be forced to contend with his own previous and contradictory position. For many years he claimed that disclosure is the silver bullet that will slay corruption and the appearance of corruption in the pay-to-play world of Capitol Hill.

During the years (yes, years!) when the Bipartisan Campaign Reform Act was being debated in Congress, the Republican leadership, led by McConnell and former House Majority Leader Tom DeLay, repeatedly argued that there was no need for new regulations, just more disclosure. “We need to have real disclosure,” McConnell told a nationwide audience on “Meet the Press” at the time.

That is exactly what the DISCLOSE Act would do. The measure seeks to strengthen the current disclosure requirements — the very tact that McConnell and DeLay heralded as the best way to approach money in politics — and already the sharp knives are out. Accusations of partisanship are being bandied about, largely because the bills are being carried by Democrats who are or were recently chairmen of their party’s campaign committees.

McConnell has chosen to disregard the content of the DISCLOSE Act and his own professed affinity for disclosure in order to condemn the legislation as an “effort to disregard the First Amendment and defy the Supreme Court in order to limit the speech of those who may disagree with you.”

The best way to fight back against this disinformation campaign is to ensure that the legislation is indeed judged on its merits and substance. If Senators of both parties can get past the noise, the bill will have a good chance of passing. Thoughtful Members from both parties understand that, post-Citizens United, the stakes are high, and the potential of millions of unaccountable corporate dollars flowing into elections is enormous. Most of the attention has focused on potential corporate expenditures, and reasonably so, because the potential pool of such funds is gigantic.

However, corporations should be a bit reticent about jumping to the game logo first, given they have a variety of potential minefields to manage with shareholders and consumers, not to mention politicians. Unions, on the other hand, are generally less risk-averse and are likely to be much more active in the midterms.

The disinformation has extended to descriptions of current law and regulation as well. Claims that contributions made to third-party groups (like the Chamber of Commerce) for independent expenditures are already fully disclosed are inaccurate. If a group does not specifically designate its contributions for the organization’s electioneering communications, then it avoids disclosure. A contribution made to the general treasury of an organization that is then used to help fund ads is not disclosed, and Federal Election Commission rules to some degree create a road map for evasion. Supporters of the bill need to call out this practice for what is — “money laundering.”

The point is not to require disclosure of an organization’s donors; rather, to ensure disclosure of those individuals and groups that spend significant amounts of money intended to influence our elections.

At the end of the day, each Republican Senator will have to gauge whether voting against the DISCLOSE Act is worth the risk of angering his constituents who are fed up with the influence of corporations, unions and well–heeled special interests in D.C.

A vote against this bill is a vote against disclosing who is buying seats at the table behind the closed doors where deals are cut and decisions are made in Washington. Beyond contending with the mood of the nation, Republicans will also have to wrestle with the idea of following a Minority Leader on this issue who was for disclosure before he was against it.

Meredith McGehee is the policy director of the Campaign Legal Center and has advocated for campaign finance reforms for more than 20 years. She also heads McGehee Strategies, a public interest consulting business.