Senate Democrats, under pressure from a White House arguing separation of powers, rejected a GOP attempt Thursday to provide greater transparency and congressional oversight of 18 so-called czars appointed by the Obama administration without Senate confirmation.

Democrats employed a procedural tactic to kill the GOP proposal, which would have withheld federal funds for the creation of any new, unconfirmed czar positions until the administration agreed to allow the individuals to testify before Congress under "reasonable" requests. 

The proposal also would have required every czar to produce a detailed "public, written report" biannually of their actions and involvement in the creation of policy, rules, and regulations.

But Democrats used a Senate rule that prohibits legislating on a spending bill -- something that is often done by both political parties despite the rule -- to kill the measure.

Sen. Susan Collins, a moderate Republican from Maine who sponsored the amendment to a spending bill that funds the Interior Department, decried the move on the Senate floor, saying she was "deeply disappointed" in her Democratic colleagues.

"My amendment has been carefully tailored to cover officials that the president has unilaterally designated for significant policy matters," said Collins, who is the top Republican on the Homeland Security and Governmental Affairs Committee.

"It would not have covered the president's chief of staff, for example, and it would not cover less senior White House officials, despite some misinformation to the contrary," Collins said, noting that her staff had worked with White House officials Wednesday night without agreement.

Senate Democratic Whip Dick Durbin, D-Ill., a close ally of the White House, was not convinced. He said he sensed a more politically-motivated attack by "czar watchers," invoking "the political wiseman" FOX News' Glenn Beck, as well as Sen. Kay Bailey Hutchison, R-Texas, who Durbin said had found a larger number of czars than Collins, who detailed 18 unconfirmed czars for the record. 

Durbin noted that both Beck, who he jokingly called a "political adviser," and Hutchison had come up with the same number of czars, 32, which included positions that are confirmed by the Senate.

"Who's going to define who is covered by your amendment?" Durbin implored. He also noted that the workload the Collins amendment would have imposed on the czars would be onerous.

But Democrats earlier in the week appeared to be on the cusp of accepting the amendment without objection.

Sen. Dianne Feinstein, D-Calif., manager of the Interior spending bill, had told Collins that Democrats were prepared to include her amendment, though one objection had popped up. At the time, Collins told FOX News that it appeared to be a simple misunderstanding. 

Soon after, it became clear the White House had objections. Feinstein told FOX News on Thursday that the White House had told her to back off.

"It's a huge separation of powers issue," the California Democrat said. "I had no idea."

Durbin listed czars used by former President Bush, as well, which he said numbered 47, though Collins appeared to disagree, saying "there wasn't this kind of proliferation" under Bush. Collins said her effort would be the same no matter who occupied the White House.

"Regardless of whether it's a Democratic president or a Republican president, a Democratic Congress or a Republican Congress, I think this is an institutional issue," she said. "And I think all of us as members of Congress should be very concerned about organizational structures that make it impossible for us to conduct productive, conventional oversight."

Durbin refused to bend and instead offered a consolation prize.

"The good news is this: Our trusted friend Joe Lieberman (chairman of the committee on which Collins serves)...has promised a hearing on this issue," he said.