Today we publish a commentary by Senate Minority Leader Mitch McConnell (R-Ky.), arguing against legislation to require expanded campaign finance disclosure. The senator points to the current furor over how the Internal Revenue Service (IRS) mishandled applications from tea party and other conservative groups for tax-exempt status under Section 501(c)(4) of the Internal Revenue Code. We certainly agree with him that the IRS failed to meet basic standards of fairness in selectively pressing the groups for more information and in delaying their applications.

Mr. McConnell writes that the IRS scandal shows that political donors must be protected from possible “intimidation” by the government, that Washington is out to “target people because of their beliefs.” This is an awfully dark view of national government under any administration. Such practices are common in other countries but not in the United States. The IRS failure was an exception, and a bad one, but not the rule.

Meanwhile, the political process is sliding backward toward the practices of the years before the Watergate reforms. More than $300 million in secret contributions were spent by outside groups in the 2012 presidential and congressional races. In the last cycle, a large share of the hidden cash was channeled through 501(c)(4) tax-exempt organizations. And here’s a key fact that often gets overlooked: Under the rules, these organizations have to disclose their donors to the IRS. Only the public remains in the dark.

Secrecy denies vital information to voters about who is contributing to which candidates. Very often, these contributions are made in search of influence on policy. We think openness here is a more valuable public good than is providing a cloak for every fat cat who wants to remain hidden.

The two main parties once agreed that disclosure should be a pillar of campaign finance. In 2010, the Supreme Court’s decision in Citizens United v. Federal Election Commission opened the door to unlimited contributions by corporations, wealthy individuals and labor unions. It should not be forgotten that in Citizens United a majority of the court reaffirmed the importance of disclosure. But having won on the issue of contribution limits, many Republicans abandoned their previous support for disclosure.

An attempt toward more transparency was made in the last Congress with the Disclose Act, but the measure was blocked by Republicans. Now Sen. Ron Wyden (D-Ore.) has joined with a Republican, Sen. Lisa Murkowski of Alaska, to offer a fresh attempt at a bipartisan bill, the Follow the Money Act, which, they declared, will cover “the full universe of independent political spenders.” One welcome idea in the bill is real-time electronic reporting and disclosure of contributions. It is not clear whether the mechanism of the bill would deliver the worthy goal of universal coverage, but there is time to hammer out details. It’s significant that Ms. Murkowski has become the first Republican in a while to sign up for a campaign disclosure bill, and we hope she can persuade others to join her.

Rep. Chris Van Hollen (D-Md.) reintroduced the Disclose Act in January, and a version is expected to be introduced in the Senate by Sheldon Whitehouse (D-R.I.). This legislation also has valuable provisions, such as requiring corporations and unions to disclose their campaign-related spending to shareholders and members.

The road to passage for any legislation this year is going to be uphill, but the push for greater openness deserves support. In a political system saturated with cash, transparency is the last, best hope for accountability.