FAIRWAY, KS — On May 15, hundreds of demonstrators gathered outside the state Capitol in Lincoln, NE, to protest the filibuster that has blocked a bill expanding Medicaid to 54,000 new patients in the state, in accordance with the federal Affordable Care Act.

The demonstrators knew what they were protesting against. But they didn’t know exactly whom.

Here’s the situation: while the healthcare reform law envisions a major Medicaid expansion and commits federal funds, the Supreme Court’s ruling on the law said states must have the option to reject the program’s growth. Dave Heineman, Nebraska’s Republican governor, opposes expansion, but proponents have been organizing support since last year, and they reportedly have a majority in the state’s 49-member, nonpartisan, unicameral legislature—and are close to the 30-vote supermajority needed to override the governor’s veto.

Under the rules of the state legislature, though, the threshold to overcome a filibuster is even higher: 33 votes. So opponents have seized on that strategy. Since lawmakers debated the Medicaid bill for 10 hours in mid-April, the measure has been bottled up by a filibuster, and it now looks unlikely to be revived before the session ends on June 5.

But despite the huge stakes of this debate, the legislators who have held up the bill for more than a month remain largely in the shadows. And a much-discussed “pledge” not to vote for cloture, apparently signed by those senators, remains out of public view.

“In an open legislative process, it is odd that we apparently have not yet seen the list of senators who signed that pledge,” Lincoln Journal Star columnist Don Walton wrote on May 12. “Or did I miss something?”

Apparently not. Most news reports about the stalled bill, even in Walton’s own paper, have not focused on the identities of the filibustering senators—typically mentioning only that there is a filibuster, without naming names.

That’s a reflection, in part, of editorial choices. “It’s not been a major focus of my coverage,” Martha Stoddard, statehouse correspondent for the Omaha World-Herald, told me in an interview.

But it’s also because the lawmakers who oppose expansion have deliberately kept details of the filibuster blurry. JoAnne Young, statehouse reporter for the Journal Star, told me that she has tried to find the “supposed memo or e-mail or letter” signed by the pledged senators, but that her efforts have been stonewalled.

“It’s not that we don’t think it’s important,” said Young, perhaps the only reporter to identify any of the pledge-signers by name. “Nobody’s been able to see that. A lot of senators have asked to see that and been turned down. We’ve asked to see that and been turned down.”

In fact, Stoddard told me, “Some of the people who appear to be the leaders of this have denied [the pledge] exists.”

One senator put the lie to those denials, however, when he announced at the beginning of this month that he was breaking ranks from the anti-cloture bloc.

“Earlier in the year, I had ‘pledged’ not to support the bill and had my name added to a list that had enough senators on it to prevent a cloture vote and thus prevent a vote on the bill,” Sen. Jerry Johnson wrote on his legislative website on May 16. “I thought long and hard about this pledge and the matter at hand…. I came to the legislature expecting to vote on issues not tactics and most of you that have contacted me on both sides of this issue want me to vote. I got up and removed my name from the pledge list.”

Johnson added, “I do not support the bill but I do feel Nebraskans deserve a vote up or down on the issue.”

At the same time that Johnson announced his defection, two other senators—Ken Schilz and John Murante—told the Journal Star’s Young that they had signed the pledge and would honor it. But while a few senators have been quoted either opposing or supporting the underlying bill, no other pledge signatories have been identified in news coverage to date, as far as this reporter could determine.

There are some likely suspects. Jim Cunningham of The Catholic Voice in Omaha, in his account of the legislative debate in April, listed several senators who spoke on the floor in favor of the bill and against. Vocal opponents included Sens. Charlie Janssen, Bill Kintner, Beau McCoy, Jim Smith, and Lydia Brasch. Janssen, in fact, explicitly argued against cloture in the April 17 session, and Kintner has strongly hinted on his legislative website that he is a part of the filibuster.

Deron Lee is CJR's correspondent for Iowa, Missouri, Kansas, and Nebraska. A writer and copy editor who has spent seven years with the National Journal Group, he has also contributed to The Hotline and the Lawrence Journal-World. He lives in the Kansas City area. Follow him on Twitter at @deron_lee.