After failing last week in their efforts to nudge Sen. Robert Byrd to voluntarily step down as chairman of the Appropriations Committee, Senate Democrats are looking toward the next few weeks to see if the West Virginia Democrat can fulfill his duties atop the all-important panel.

Byrd vowed to be more vigorous in his stewardship of the committee during a round of targeted calls to influential Democratic Senators last week. Now, the ailing, 90-year-old Senator will be expected to make good on those pledges by chairing a markup of the $100 billion-plus supplemental war spending bill at the end of April or beginning of May, Democratic sources indicated last week.

Byrd’s promises followed a Tuesday Senate Democratic leadership meeting at which Members discussed whether Byrd, who has been in and out of the hospital in recent months, was still capable of shepherding the massive supplemental through the panel and the Senate this year.

There also was talk about the need to hold a full committee hearing on the supplemental in the next week or so in advance of the markup, but one had not been scheduled by late last week.

If Byrd remains in place, however, the schedule for the supplemental could prove problematic for Senate Democrats given Byrd’s often erratic performance over the past year during hearings and markups. Just last week, Byrd asked Sen. Tom Harkin (D-Iowa) to cancel a long-planned subcommittee hearing on mine safety that the chairman planned to attend, given the topic’s import to coal-rich West Virginia.

Byrd himself hasn’t managed a bill on the floor for more than a year, and he has not chaired an Appropriations hearing or markup since September 2007, when the panel played host to Defense Secretary Robert Gates and Secretary of State Condoleezza Rice.

During that hearing, he spoke at length about the problems he perceives with the Bush administration’s Iraq policy, and he asked several questions of both witnesses.

But other hearings were not so smooth. In fact, questions about Byrd’s fitness as chairman began at an April 12, 2007, hearing on tainted pet food from China, sources said.

At the hearing, Byrd gave a rambling speech about his dog, Trouble, and spoke simultaneously of not knowing whether he would live through the next year and of running for re-election in 2012, when he will be 94.

“I’m not getting ready for any re-election right now. I will run in 2012, the Lord willing. That’s all between you and me,” Byrd said in an apparent attempt to prove to the packed committee room that he was not grandstanding. “But I am the chairman of the Appropriations Committee, for the audience to know. I’ve been a Senator for 49 years, and the Lord willing, next year I will be a Senator and I will have been a Senator, with the Lord’s will, 50 years, if I live through it.”

Byrd did chair full committee markups of annual spending bills last year. However, during the times that Byrd has wielded the gavel, it has been under the close watch and counsel of his staff, who have been seen at hearings apparently coaching him on what to say and when to say it. Indeed, there have been rumblings among Democrats that Byrd is being ill-served by his staff, who many see as pushing the aging chairman to stay on longer than he should.

Byrd’s spotty record of chairing the Appropriations Committee hasn’t been a major problem so far this year, since much of the panel’s work begins in the spring and heats up during the summer. But eyebrows were certainly raised when Byrd’s office unexpectedly canceled the weeks-planned hearing on mine safety, which had been scheduled for last Thursday.

Some speculated Byrd decided to postpone the hearing at the last minute to avoid further scrutiny of his health, which certainly would have been highlighted in any public forum. Byrd has been confined to a wheelchair since February after he suffered a fall at his home.

While he was hospitalized for both the fall and a urinary tract infection in March, Byrd missed two hearings he was supposed to chair — a March 4 Subcommittee on Homeland Security hearing that was anchored by Sen. Daniel Inouye (D-Hawaii) and a full committee hearing on contracting abuses in Iraq that was taken over by Sen. Patrick Leahy (D-Vt.).

However, Democrats say the clock cannot run indefinitely. Senators said privately last week that they are worried that Byrd’s worsening health has rendered him unable to lead the party’s charge as it wades through the politically charged supplemental bill.

With that in mind, it remains unclear whether Democrats will take action to sideline Byrd as chairman prior to the supplemental debate or whether another appropriator, perhaps Conference Secretary Patty Murray (Wash.) or the panel’s senior members, Inouye or Leahy, will temporarily take over the committee during the supplemental debate.

Murray in particular handled many of Byrd’s floor duties over the past few years during some of the Senate’s key appropriations debates. Murray also chaired the conference on the 2007 supplemental war spending bill. Meanwhile, Leahy steered the omnibus appropriations bill on the Senate floor in December.

As of press time Friday, a Byrd spokesman did not respond to a request for comment on whether Byrd planned to chair any future markups or hearings.

Despite Democratic leaders’ efforts to push Byrd to the conclusion that he should no longer serve as chairman, Byrd’s round of calls arguing that he is still up to the job appears to have given him some breathing room.

Sources familiar with the sensitive matter said Byrd now appears steadfast in trying to hang on to the position. And because of that, Democratic leaders, already reluctant to take on the uncomfortable task of displacing the revered senior Senator, have decided to back off on pressing the issue — at least for now.

Still, Senators on the panel were making the rounds last week to assure Byrd that he still has their support.

Sen. Ben Nelson (D-Neb.), an appropriator, said Thursday that he approached Byrd on the floor to tell him, “You’re my chairman.”

He added, “Sen. Byrd has made it clear he’s staying.”

When asked what Senate Democrats plan to do since Byrd clearly isn’t prepared to move aside quietly, one source said: “Members are waiting to see what if anything happens next. The concerns are still there.”