PRESIDENT OBAMA’S money men have taken a welcome step away from the ethical abyss: They will now disclose the names of those who donate $250 or more to the new advocacy group Organizing for Action, which is intended to advance the president’s second-term agenda. Jim Messina, the group’s national chairman, promises to post the donors’ names and the precise amount of their donation quarterly on the group’s Web site. This transparency is critical to avoid the corrupting influence of hidden contributions. If someone wants to put $1 million or more on the table as a way of seeking influence with the president, at least it will now be visible.

The new tax-exempt organization is being formed under Section 501(c)(4) of the Internal Revenue Code, a broad category for tax-exempt “social welfare” groups. Federal rules do not require public disclosure of donors and amounts to such groups, as would be required if they were operating under the rules of the Federal Election Commission. Some other organizations formed in this category, such as Karl Rove’s Crossroads GPS, have kept the names of their donors secret.

Mr. Messina also reversed course on corporate donations and, in a commentary for, said they would not be accepted. Earlier, he had ruled out money from federal lobbyists or foreigners. This will help close off the temptation of firms to curry favor from the administration by making contributions.

But the fact remains that Organizing for Action still presents an opportunity for abuse. Mr. Obama is no longer a candidate but a sitting president. To encourage individuals to make unlimited contributions to a group closely associated with him is unseemly. Mr. Messina declared, “[W]e can’t and we won’t guarantee access to any government officials,” but then he went on to describe “updates” and “briefings” that Mr. Obama and the administration will deliver “on the legislative process,” to which the donors and volunteers will be invited. “These are not opportunities to lobby,” he said. Nice thought, but will it deter a big donor determined to speak to the president? Let’s not be naive about access for donors — it has been going on for a long time, often in the shadows. It is no less objectionable that the president is now setting up a formal structure that might dish out access in the same way.

Mr. Messina has portrayed the new group as a grass-roots counterweight to the “special interests” and an attempt to “rebalance the power structure” away from the “highest paid lobbyists on K Street.” Undoubtedly, Mr. Obama has a valuable tool in his enthusiastic, Internet-savvy army of followers. But by soliciting unlimited contributions from individuals, and giving them access to the White House, Mr. Obama undermines the claim that he is above the special interests and comes across as just another hawker in the unlimited-money sweepstakes.