At first glance, the swearing in of a new Congress today marks a concentration of power for George W. Bush that is nearly without precedent in the post-World War II period.
For the first time since 1954, a Republican president is matched with a Republican-majority House and Senate - a Congress his campaigning helped create.
But Mr. Bush, while holding the political high ground, will not find a rubber stamp at the end of every gavel on Capitol Hill.
He clearly wants and expects to set the agenda on everything from Arctic oil drilling to prescription drug benefits. Today, he unveils a major new tax-cutting plan to stimulate the economy.
Yet both Houses of Congress remain only narrowly under Republican control. Democrats are sure to find ways to parry White House goals, whether by Senate filibusters or peeling some Republicans to their side on key votes.
And, while GOP leaders in general are closely allied with Bush, Republicans themselves could prove nettlesome to the Bush agenda. In the Senate, many incoming GOP committee chairmen are lining up agenda items that are off - or even at odds with - Bush's wish list.
Tomorrow, for example, Sen. John McCain (R) of Arizona plans to chair hearings on a sweeping proposal to address global warming by mandating reductions in US greenhouse-gas emissions, something the White House opposes.
Indeed, a hallmark of the Senate is to resist taking direction either from House colleagues or the White House.
Senate Democrats, for their part, are regrouping after midterm losses that surprised many here. Sens. John Kerry of Massachusetts and John Edwards of North Carolina have already announced bids for the presidency in 2004, with several others likely to join them.
The Senate of the 108th Congress is even more than usually in flux. It convenes with a heavy load of unfinished legislative business, including 9 of 11 spending bills for a fiscal year that is now into its second quarter. Nor has the outgoing Senate leadership resolved how to reorganize committees and staff, after a historic power-sharing agreement ran out at the end of the last Congress. Until they do, Democrats will continue to control committees.
At the same time, Senate Republicans are quietly binding up wounds after a leadership coup last month - the first in Senate history. After talk of a "soft landing" for outgoing Republican leader Trent Lott, Sen. Rick Santorum of Pennsylvania, who ranks No. 3 in the GOP leadership, offered to give up his own chairmanship of the Rules committee to find a spot for Mr. Lott.
The move is a sign of how deep feelings are still running after an ouster that stemmed from racially charged remarks Lott made. Even some who approved his fall from power chafe at what some felt was White House interference in favor of the ouster.
Had Lott opted to resign from the Senate, his replacement would be named by Mississippi's Democratic governor - likely bringing the Senate back to an effective 50-50 split, with Independent James Jeffords of Vermont voting with the Democrats.
After Mr. Jeffords dropped out of the GOP in June 2001, Democrats used their new control of the Senate to sideline much of the Bush agenda, including an overhaul of energy policy, permanent tax cuts, a prescription drug bill, and dozens of judicial nominees.
Now, the job of getting that agenda back on track falls to Sen. Bill Frist, who replaces Democrat Tom Daschle as Senate majority leader. Famously energetic and an accomplished surgeon before running for the Senate in 1994, Mr. Frist brings a fresh face to the GOP leadership, but not much legislative experience. Some colleagues have never seen him chair a meeting.
He's also unusually close to the White House, where he has worked closely with President Bush on health policy and campaign strategy for the midterm elections.
But colleagues in the GOP caucus will also be looking to Frist to defend the interests of the Senate, even as he advances a Republican agenda. That may mean taking on the White House early on.
"There is going to be a point where Frist is going to have to assert the independence of the Senate on some issue ... to demonstrate to his colleagues that his judgment on the inner workings of the Senate is what counts and not the views of the White House," says Michael Franc of the Heritage Foundation in Washington
Many GOP committee chairs, too, are staking out their own agendas for the new Congress.
The most freewheeling and visible of them is Mr. McCain, who has already announced an ambitious schedule of hearings for the Commerce, Science and Transportation committee on issues ranging from cable rates to corporate governance.
On global warming, the bill McCain is sponsoring with Sen. Joseph Lieberman (D) of Connecticut, is encouraging to environmental groups that had expected nothing but bad news from a GOP-controlled Congress.
"A lot of people in our community were anticipating that the only political energy out there would be focused at rolling back environmental protection," says Joseph Goffman of Environmental Defense, a Washington lobby.
Another chairman with a strong record of independence is Sen. Charles Grassley of Iowa, an outspoken critic of executive branch efforts to keep information from Congress and the public. As new chairman of the Senate Finance Committee, he expects to pass on up to 70 percent of the major issues before the Senate.
In 2001, he and ranking member Max Baucus (D) of Montana defied the leadership of both their parties by reaching agreement on a $1.35 trillion tax cut - below the $1.6 trillion the White House had proposed but well above what the Democratic leadership was prepared to accept. The bill that came out of their committee passed the Senate with 12 Democratic votes.
Does Grassley expect the White House to set the agenda for a new Congress? "Absolutely not. Nothing gets done in the Senate if it's not bipartisan," he says, adding that a strong "working relationship with Senator Baucus" will be "the basis of all we do."
Also with quiet clout in the new Senate is Richard Lugar of Indiana, who takes over as chairman of the Foreign Relations committee. A consensus builder with deep experience in foreign affairs, he plans committee hearings to focus the Bush administration's attention on the resources needed to rebuild Iraq after a possible war or UN-monitored disarmament. "The point of the hearings ... is to stimulate that planning on the part of our government," he said in a Dec. 19 briefing for foreign press.