After staying relatively quiet for more than a week at Speaker Nancy Pelosi’s (D-Calif.) request, Senate Democrats re-engaged in the health care debate Wednesday as the push for an overhaul began to reach a critical stage in both chambers.

At a special midday caucus, Democratic Senators were asked to finally put their necks on the line by signing a letter — co-written by Pelosi’s staff — expressing their general support for pushing the health care reform bill to final passage through the budget reconciliation process. House leaders have asked that, before they ask their Members to vote on both the Senate-passed bill and the reconciliation “fixer” package, the Senate show they have the 51 votes necessary to clear reconciliation through the chamber.

The letter was not available before press time, but Senators and aides said it would put Senators on record as supporting a number of principles the reconciliation bill is expected to address. But without bill language for Senators to expressly endorse, the letter could fall short of the ironclad promises many wavering rank-and-file House Democrats want.

“We talked about showing strong support for the House as they move forward,” Sen. Amy Klobuchar (D-Minn.) said of expected House votes this weekend. “There wasn’t a discussion about doing a letter that specifically says we will vote for reconciliation when we haven’t seen the bill. But a letter showing that we were generally supportive of moving forward on health care, we thought that that would be helpful.”

Though Senate Democratic leaders expressed confidence that they would have the support of more than 51 Members for reconciliation, not all of those Senators were willing on Wednesday to sign the letter.

[IMGCAP(1)]”I want to see all the details before I sign it, but I generally think … if we have to improve or fix a few things in reconciliation that that would be the right process,” Sen. Mary Landrieu (D-La.) said. “The letter is being circulated and, I think, made public so that the House will feel comfortable that there’ll be enough people here to support it, but I have to see the details before I sign it myself.”

At press time, leaders anticipated having a preliminary cost estimate of the measure from the Congressional Budget Office on Wednesday night or today.

Majority Whip Dick Durbin (D-Ill.) said after Wednesday’s caucus meeting that leaders had asked Members “who may have a problem with [signing a letter] to let us know.”

He said that with or without a Senate letter, he has “a positive feeling” about getting enough Democrats to support reconciliation on final passage.

But without a bill to point to, leaders were left to talk in generalities as they waited for the package to be finalized and a CBO score to emerge.

Senate Finance Chairman Max Baucus (D-Mont.), however, confidently predicted the reconciliation measure would come in at or under President Barack Obama’s $950 billion cap for health care reform. Aides said the final touches being put on the reconciliation bill are intended to increase the measure’s deficit-reduction numbers.

Senators and aides also said the writing of the bill has been laborious as Senate Democrats look to craft it in a way that would not expose the measure to potentially crippling Republican budget points of order.

GOP Senators have vowed to mount an aggressive floor campaign against reconciliation to try to prevent the Senate from clearing the fixer measure for the president’s signature. But even if reconciliation were to fail in the Senate, House passage of the Senate-passed comprehensive health care bill would ensure the bulk of Democrats’ reform initiatives become law.

One Senate Democratic aide said leaders were about “80 percent” certain that reconciliation would not be subject to points of order that require 60 votes to waive. If points of order are not waived, sections of the bill will be removed for a lack of compliance with the strict rules governing reconciliation.

The Democratic aide cautioned that 100 percent certainty is not possible because of the way the Senate Parliamentarian’s office works and the ability of Republicans to make their own arguments for points of order once a bill is publicly available. The Parliamentarian is the arbiter of what meets the requirement under reconciliation that all provisions have a budgetary impact, but Members are allowed to present arguments for and against specific provisions.

Sen. Debbie Stabenow (D-Mich.) acknowledged that the bill’s potential vulnerabilities to points of order are high on Senate leaders’ minds.

“We have to watch that every step of the way,” she said.

House and Senate leaders decided to use the reconciliation process because it would allow them to make fixes to the Senate-passed bill without encountering a filibuster. The special election of Sen. Scott Brown (R-Mass.) in January robbed Democrats of the filibuster-proof majority they used to pass their original bill in December. House leaders plan to pass the Senate bill at the same time they vote on the fixer package, likely this weekend.