A bill requiring super PACs and other outside political groups to include the names of top donors on their ads will hit the Senate floor next month, Sen. Sheldon Whitehouse, D-R.I., said Friday. Meanwhile, an unlikely source warned the Republicans who are expected to filibuster it that they are standing in the way of the inevitable. 

Whitehouse's comments came in his home state at a conference of liberal bloggers, where he was on a panel about the effects of Citizens United, a 2010 Supreme Court case that opened the door for unlimited campaign spending by corporations and unions. 

Meanwhile, on Capitol Hill, a scholar at the libertarian Cato Institute offered some unsolicited advice to congressional Republicans: Act on a disclosure bill soon because history is on its side. 

The prediction from John Samples, director of the think tank's Center for Representative Government, was surprising because he's not a fan of  DISCLOSE 2012, versions of which have been introduced this year in the Senate by Whitehouse and the House by Rep. Chris Van Hollen, D-Md. It would require independent groups such as super PACs and 501c4s running election ads to disclose their donors and add disclaimers to the ads. The head of the group running the ad would appear in it, and its top five donors would be listed. The bill would also extend the period when ads—called electioneering communications—would have to be reported to the Federal Election Commission. The Sunlight Foundation supports the legislation.

Samples does not support the current version of the bill, saying it chills speech and leads to a less rational public debate because it leads to demonizing individuals behind the ads. He said that longtime donors—such as George Soros and Bob Perry—are used to being in the headlines and so are not turned away by the disclosure. But he argued that it discourages a corporate CEO from donating. 

But he said—in effect—the train is moving so you better get on it. 

"Maybe it's better not to wait. Maybe it's better to think of something more productive for everybody," said Samples.

He said it's unlikely the bill will move in this Congress.

"When one side thinks they're doing very well in the system…they're not interested in changing that." In this election cycle, Republicans think the outside groups will help them outspend President Obama, Samples said.

Whitehouse has 44 co-sponsors of his bill, far short of the 60 required to overcome the anticipated filibuster. Sen. Jeff Merkley, D-Ore., who joined Whitehouse on Friday's panel at the Netroots conference in Providence, said backers of the DISCLOSE legislation planned to force round-the-clock sessions to dramatize the opposition of the bill and asked members of the audience whether they would be willing "to do an all-night or many-night blog in to stir up the country?" The response was an ovation.

Samples believes legislation like DISCLOSE could win passage by 2014 or 2016. That's because the history of campaign finance tells him that the other side doesn't give up, he said. In the 1990s, he noted, Democrats were being out-fundraised by Republicans but pulled even by 2002. He said the GOP's current edge in outside money similarly will disappear.

In swing districts in 2014 and 2016, "super PAC armadas" supported by the likes of George Soros are going to start showing up in swing districts, targeting Republicans, Samples predicted. As a result, he said, Republicans may come to dislike Citizens United.

Another argument in favor of his theory: if Democrats can 90 percent of votes on something, as they easily did in the Senate vote on DISCLOSE 2010, than they can get 20 percent of Republicans on board, he said.

One more reason he offered: Minority Leader Mitch McConnell, a Kentucky Republican who has been a leading opponent of legislation designed to regulate money in politics and "a tremendous source of support for free speech," in Samples' view, may not be in power forever, the Cato scholar noted.

Photo: Floor art at Netroots Nation by Billy Wimsatt of Rebuild a Dream (Kathy Kiely)