A membership shakeup on the Senate Budget Committee could give GOP leaders the extra muscle they need to push through most of President Bush’s contentious fiscal 2004 domestic budget plan.

Largely because of the availability of more desirable committee spots, three relatively unreliable votes for the GOP leadership — Sens. Olympia Snowe (Maine), Chuck Hagel (Neb.) and Gordon Smith (Ore.) — decided to leave the Budget Committee this year.

With more conservative lawmakers now in place on the Budget panel, senior GOP aides predict a slam dunk for setting aside at least $674 billion for Bush’s proposed tax cut when the committee marks up a budget resolution in mid-March. Of course, that number could rise as well.

“With our committee members, we could probably double the president’s [tax cut] number,” said one senior GOP aide. “We’ve got a lot of guys who like tax cuts.”

Snowe and Hagel traded seats on Budget for spots on the now-coveted Select Intelligence Committee. Smith joined the powerful Finance Committee as well as the Energy and Natural Resources, Rules and Administration, and Indian Affairs panels. He also sits on Commerce.

Mindful of past difficulties in getting those swing votes to agree to a committee budget resolution, Republican leaders stacked the committee with a host of dependable conservative votes — Sens. Jim Bunning (R-Ky.), Conrad Burns (R-Mont.), John Cornyn (R-Texas), Mike Crapo (R-Idaho), John Ensign (R-Nev.), Mike Enzi (R-Wyo.) and Jeff Sessions (R-Ala.).

The departures of the three moderates, plus the loss of new Senate Majority Leader Bill Frist (R-Tenn.), Sen. Kit Bond (R-Mo.) and recently retired Sen. Phil Gramm (R-Texas), opened up the Budget panel for those seven new GOP members.

“If it’s just coincidence, it’s hard to believe,” said one Senate Democratic aide. “It certainly suits their effort and purpose for pushing more tax cuts.”

Interestingly, Sen. Lincoln Chafee (R-R.I.), a moderate and a deficit hawk who has been skeptical of Bush’s latest tax-cut plan, was not notified that a spot was open on Budget, according to a Chafee aide, even though he outranks both Ensign and Cornyn in overall Senate GOP seniority.

“They’re not going to want to see the more moderate people on Finance or Budget,” the Chafee aide said of Senate GOP leaders. The aide noted that Chafee would have likely accepted a spot on Budget had he been given the option.

Senate Republican Conference rules indicate that committee spots should be offered to members on the basis of seniority in the first two rounds of committee assignments. In the third round of assignments, Frist appoints members.

Only five veteran Budget members remain of the 12 GOP members: new Chairman Don Nickles (R-Okla.), former Chairman Pete Domenici (R-N.M.), Finance Chairman Chuck Grassley (R-Iowa), Health, Education, Labor and Pensions Chairman Judd Gregg (R-N.H.) and Sen. Wayne Allard (R-Colo.).

Nickles said he would start out with the president’s proposed number for the tax cut and entertain GOP efforts to increase it, while opposing Democratic efforts to reduce it.

As one senior GOP aide put it, “We want our people to be comfortable with the number, because every [Democratic] amendment on the floor is going to be to reduce the tax cut and spend it on ‘X.’”

Nickles acknowledged that he also will likely tinker with the president’s overall budget numbers in an attempt to create a consensus with moderate Republicans who are not on the committee. Still, the makeup of the committee could help prevent the sometimes long delays the budget resolution faced to committee markup in the past — even if Republicans have to send the budget to the floor based on a partisan committee vote.

“It’s been a couple of years since we’ve had a really bipartisan budget resolution in committee,” said Nickles. “I’d be willing to make some adjustments to the budget if [Democrats] will support it. But I’m not going to do that if they won’t vote for the budget.”

Domenici skipped the committee process in 2001 when he was trying to shepherd Bush’s $1.6 trillion tax cut through Congress. Although Domenici ensured the votes of moderates on the panel, he was faced with an unfavorable vote, because Democrats on the committee were unanimous in opposition. At the time, Democrats had even representation on the committee because the Senate was split 50-50.

Despite the cadre of loyalists on the committee, Bush administration officials said it does not want to leave anything to chance this year. Administration officials are making a spirited effort to make sure Republicans on the Budget Committee are not just mildly supportive, but firmly behind the president’s proposal, especially the tax cut.

“We need to make sure we’ve got the votes on Budget to get the budget we need,” said a senior Bush administration official. “We don’t want our Republicans to think we’re taking them for granted. We want to make sure they’re comfortable with the proposal.”

The White House believes that the key to getting the entire tax package lies in winning passage of its entire budget, and they remain concerned about the cool reception the tax cut initially received from even conservatives on Capitol Hill.

The budget resolution, which is nonbinding, only provides an overall blueprint for Congress to follow; the authorizing committees and Appropriations panel are in charge of implementing the actual budget numbers.

But the Bush official noted that “if Budget [in both chambers] produces the number we need, it may have an impact” on the deliberations of the Senate Finance Committee and the House Ways and Means Committee, which will have to write the actual tax-cut bill and which harbor far more moderate Republicans.