Most Senate Democrats continued on Tuesday to oppose a moratorium on earmarks, despite growing public demands for an end to the practice and a nascent reform movement within their own ranks.

Reformers, including Sen. Claire McCaskill (D-Mo.), said that while passing a ban in the next few months may not be in the cards, they nevertheless believe momentum is on their side.

Asked if the earmark ban is facing a now-or-never situation in the Senate, McCaskill said, “I’m not sure that it is ever going to be never. I think it’s only a matter of time.”

Sen. Mark Udall (Colo.) — the latest Democratic convert to the anti-earmark team — agreed, saying that his colleagues are increasingly open to the idea.

“I’m hearing some expressions of interest more and more from my colleagues,” he said.

But as McCaskill and Udall joined Republican Sens. Tom Coburn (Okla.) and John McCain (Ariz.) to push for a mandatory three-year ban, Senate Majority Leader Harry Reid (D-Nev.) threw cold water on the talk of reform.

“I don’t accept [a ban] as reform. I think it’s a tremendous step backward. It just gives more power to the executive. I am not one who believes in that,” Reid said.

“And I am not in favor of delegating my constitutional responsibility to the White House,” he added.

Reid also dismissed the efforts by McCaskill, Coburn and other reformers to force a vote on the ban this week, saying he would use his powers as Majority Leader to ensure they do not have an opportunity to offer it as an amendment to a food-safety bill that he intends to bring up.

“If I’m able to get cloture on any of the issues that I bring up, it’s not going to be open amendment process, because we simply don’t have time for that,” Reid said.

Reid is not alone in his opposition to a ban on earmarks, at least within the Senate Democratic Conference.

“I’ve fought really hard to get money for my state, and I’ve done a pretty good job,” Sen. Bob Casey (D-Pa.) said, adding that while reforms may be necessary, “I think the ban is not something I would favor.

“I think to try and sweep them aside … is a bad idea,” Sen. Frank Lautenberg (D-N.J.) said.

Other Democrats said they would be open to the possibility. “I’ll take a look at it,” Majority Whip Dick Durbin (Ill.) said.

Likewise, when asked if he would support the ban, Sen. Tom Carper (D-Del.) said, “I’m open. I’m open to change.”

The fact that Democrats like Durbin and Carper are even willing to express openness to the idea of a ban is a marked difference from previous attempts to pass a moratorium. Coburn and other reformers have agitated for years for a moratorium, slowly picking up support within their Conference.

The Nov. 2 midterm elections, which delivered significant GOP gains thanks in part to the tea party movement, have also been a significant factor in swaying Republicans and some Democrats.

Nevertheless, even some Republicans are continuing to resist the idea of a ban. The Senate Republican Conference voted Tuesday in favor of a nonbinding, two-year earmark ban for its members, but only after Sen. James Inhofe (Okla.) voiced his strong objections. While he did not block a voice vote on the resolution, he has indicated he will ignore the Conference’s earmark ban.

McCaskill acknowledged that there remains strong opposition to the idea of a ban within the Democratic Conference, and she said that even a voluntary, internal ban on the practice — similar to one that Republicans adopted Tuesday afternoon — would have difficulty passing.

“I don’t think we would be successful. There hasn’t been a huge appetite yet on this side of the aisle to stop this process. Mark Udall was a pleasant surprise yesterday and I’m hoping for a pleasant surprise tomorrow,” McCaskill said.

Jessica Brady contributed to this report.