Sen. Hillary Rodham Clinton of New York, clinging to a slim chance of winning the Democratic presidential nomination, passed up a chance to send an earmark reform measure to the Senate floor last week, deciding not to take sides in an Armed Services Committee debate in which an amendment was defeated on a 12-12 vote.

Clinton was campaigning for the presidential nomination when the measure came up.

She decided not to cast a proxy vote on an amendment that would have required earmarks in the FY09 Defense Authorization measure to be listed in the bill text and not a conference report.

Presumptive GOP nominee Sen. John McCain of Arizona, who is ranking member of the Armed Services panel and sponsor of the amendment, voted yes by proxy.

The committee vote took place behind closed doors, but details were confirmed Monday and Tuesday by sources.

McCain, Clinton and Democratic presidential candidate Sen. Barack Obama of Illinois all voted in favor of a one-year earmark moratorium during the Senate's FY09 budget resolution "vote-a-rama." Clinton, who is trying to win support for her presidential bid from Democratic senators and other superdelegates, would have been only the third of 13 Democrats on the committee to support the amendment if she had decided to cast the deciding vote.

Clinton spokesman Philippe Reines said the senator did not vote by proxy because she was not present for the markup or debate. "Because of the technical issues raised, she would like to have the benefit of her colleagues' input before taking and expressing a position on the issue," Reines said.

Former Armed Services Chairman John Warner, R-Va., offered the amendment on McCain's behalf. He said he was optimistic the vote showed growing support for listing earmarks in the text of a bill.

"It didn't win, but at least I gave it the best shot I could," Warner said. "And there's one senator who abstained. And I have a feeling if that senator had been around, I would have had it." He declined to identify Clinton as the holdout.

Two Democrats joined 10 Republicans in voting in favor of the measure, while two Republicans sided with 10 Democrats to oppose it.

Sen. Claire McCaskill, D-Mo., said Tuesday that she was one Democrat who voted with Republicans for the earmark reform. She interpreted the vote as evidence of shifting momentum in the Senate.

"This is one of those baby steps that we're going to take," McCaskill said. "Either we're going to be accountable or not."

The second Democrat was not identified.

Republican Sens. Susan Collins of Maine and Roger Wicker of Mississippi voted against the measure. Aides defended their votes.

"The senator supports transparency but had concerns regarding the amendment's impact on the military's ability to reprogram funding in order to operate as efficiently and effectively as possible," a Wicker spokesman said. "His vote against the amendment had no effect on the full disclosure already included in the bill."

Collins spokeswoman Jen Burita said the bill's transparency was adequate.

"All earmarks approved by the committee are incorporated into the bill through the committee report, and they are fully available for public scrutiny," she said. "Since the bill is already transparent, she voted against this amendment."