Senator Sheldon Whitehouse, the author of the Disclose Act that was thwarted by a Republican filibuster in the Senate twice this week, began his post-mortem press conference on a somber note Wednesday morning.

“In some respects the efforts of the last few days were particularly dark days in the history of the Senate,” he said, “in which a great number of our colleagues abandoned positions which they had held very clearly and very publicly for a long time, walked away from the clearly expressed wishes of the American people, and voted to protect something which is virtually indefensible—which is unlimited secret spending in American elections.”

Both Whitehouse and Senator Jeff Merkley expressed optimism that tough campaign finance reform would be passed sooner rather than later, however—and made powerful allegations that many Republican senators are actually on their side, but were strong-armed by minority leader Mitch McConnell this week.

“There is considerable difficulty within the GOP over the position that leader McConnell has obliged them to take,” said Whitehouse. “I’ve been told by colleagues, ‘Look, we know you’re right, but give us a chance to try to work this out within our caucus.’ ”

While Whitehouse didn’t say that Senator Lisa Murkowski made any such remarks, his characterization could accurately explain her bizarre speech on the Senate floor yesterday, in which she endorsed the spirit of the Disclose Act, at times passionately, but then said she couldn’t yet vote for it.

But according to Whitehouse, some Republican senators are increasingly anxious about standing in strong opposition to campaign finance reform. “I’ve been told that Republican senators have spoken to Leader McConnell and said ‘You’re leading us off a cliff here. This is a crazy place for us to be, defending secret unlimited spending, and we’re one scandal away from owning this mess.’”

Senator Merkley echoed those sentiments, and said there was “enormous pressure” from Republican leadership in the Senate to walk the party line and that it was causing “enormous discomfort” among many Republican senators.

Republicans, and most notably former reformer Senator John McCain, say they oppose the Disclose Act because it favors unions. (We explained yesterday why that’s not the case.) Whitehouse and Merkley both expressed frustration towards that argument.

“It’s hard for me to negotiate against a position that has no foundation in the bill itself,” said Whitehouse. “I keep asking, ‘Show me. Show me. Write something.’ Because I don’t see it. It’s not there. So if you’re going to say its there, you better come up with something that shows me how to make it work. And they haven’t. They’ve come up with zero, nothing.”

Merkley suggested the union argument was simply an exercise in messaging, to obscure a more fundamental opposition to the bill. “This is one of those talking points that comes out of focus groups when you’re looking for an argument that will persuade people, even if the argument is factually, absolutely, 100 percent wrong.”

If Whitehouse and Merkley are right about softening opposition across the aisle, perhaps strong campaign reform will come out of Congress down the line—Tuesday’s vote was only seven shy of breaking a filibuster.

But until then, both senators reiterated their strong support for action by the SEC to force publicly traded companies to disclose political spending, and for the IRS to crack down on nonprofits operating almost exclusively as political operations, like Karl Rove’s Crossroads groups. (The press conference was held in the Capitol Building by the Corporate Reform Coalition, a collection of public interest groups and institutional investors that supports SEC action and other avenues of campaign finance reform).

Merkley also called for strong public engagement—something that was already evident this week as the Disclose Act repeatedly trended on Twitter during votes and floor speeches. “When you allow oceans of undisclosed, secret, possibly foreign money to buy up the airwaves, you take away the debate that’s at the heart of our democracy, and you create a situation where these forces with billions of dollars behind them can say ‘If you don’t vote with us, we’ll be there in the next election to take you out.’ And that sort of coercion is as corrosive and corruptive in a democracy as anything we can think of,” he said.

“We need to have massive citizen’s movement,” Merkley continued, “that says we believe in ‘We the people’ and we are going to take this into the elections and we’re going to make it an issue—for the presidential elections, for the Senate elections, for the Congressional elections, for the local elections.”