So when precisely does a president become a lame duck? The moment he wins re-election? When the poohbahs on Capitol Hill cease being afraid of him? When the commentators say he’s cooked? Or – to mix metaphors and to reclaim one of Bill Clinton’s favorite lines – not until the last dog dies?

The dangerous thing for the Bush administration right now is that lame-duck talk is beginning to swirl around the White House. Social Security overhaul is going nowhere, the war in Iraq is dragging on gloomily, the economy is not exactly raging like a bull, and the boomlet of interest in Sen. John S. McCain of Arizona, fueled by a television movie, is a symbol of Bush’s political mortality – and a reminder that some antagonists within his own party are still around, still fighting and still hoping for a chance at the presidency.

Political analysts have long argued that a president’s effectiveness drops dramatically at his moment of greatest triumph, his endorsement by the voters for a second term. Congressional chairmen, regulators, lobbyists, opponents – they all know that the president’s tenure is finite (not so nasty anymore, not so brutish and definitely short) and their eyes and attention begin to wander. At least that’s the theory.

TR, Reagan disprove theory

But two Republican presidents from the last century provide ample argument against the theory.

The first is Theodore Roosevelt. He served out the remainder of William McKinley’s term after the president was assassinated in Buffalo, then sought election in his own right in 1904 and promptly announced he wouldn’t run again in 1908. In some ways, it was a colossal mistake. Washington knew it wouldn’t have Roosevelt to kick around anymore.

And yet, even after declaring himself out of the 1908 race, TR still managed to promulgate the Roosevelt Corollary to the Monroe Doctrine, win the Nobel Peace Prize for his role at the end of the Russo-Japanese War, push for and win approval of the landmark Meat Inspection Act and the Pure Food and Drug Act, designate the first national monument, negotiate the Gentleman’s Agreement with Japan, and appoint a Supreme Court justice. All ducks should be so lame.

The second example is Ronald Reagan, who wasn’t only in a term-limit situation after his 1984 victory but also was growing increasingly aged. No matter. In a second term that was overshadowed by the Iran-Contra scandal, he nonetheless won the capstone of his economic program, the tax-simplification bill of 1986, and also notched approval of a free-trade agreement with Canada (precursor to NAFTA). With new Soviet leader Mikhail Gorbachev, he began the final great thaw between the Warsaw Pact and the West. He appointed William H. Rehnquist chief justice of the United States and, though two nominees to the high court failed, won approval of Anthony M. Kennedy to the bench.

President Bush signaled from the start that he was determined to serve up a yeasty second term. He’s taken on the stem-cell issue with a relentlessness that troubles even some Republicans, especially the Reagan family, which is uneasy that the president’s position endangers important potential discoveries that could prevent or soften the onset of Alzheimer’s disease.

He roared out of the box with a Social Security overhaul plan even though there was no demand for one; his blueprint won the applause of conservative ideologues and almost no one else. In his White House news conference the other morning, Bush acknowledged it will take some time to prevail in his Social Security battle, but likened his commitment to “water cutting through a rock,” adding: “You’ve got a president … who’s going to keep talking about the issues until we get people to the table.” Not much ambiguity there.

Why not Bush?

What keeps Bush from being a dead duck politically? His age, to start. He turns 59 next month and, though ridiculed by opponents for being lazy, is still vigorous … and ambitious. Indeed, his ambition seems to grow with the years, as it does with so many late-bloomers. Then there’s the sense of momentum. Presidential adviser Karl Rove believes the Republicans are on the verge of solidifying the majorities they have in Congress, and so there is the air of a crusade about the White House. The Republicans don’t think they’re about to dismantle the power structure. They think they’re about to add to it.

Three other factors add to the president’s effectiveness.

There’s the Democrats’ ever-fiercer opposition. (He irritates his rivals, he infuriates them, he inspires them. That, in turn, reinvigorates the president.) There’s the effort to battle terrorism. (It’s not winding down, it’s only started. Anyone who hears the daily briefing report the president receives can only be sobered into paying attention.) There’s the Supreme Court.

Battles may be ahead

Nothing the president may do on domestic affairs may approach in importance what he does when he gets a chance to appoint a new member of the Supreme Court. That could come at any time, of course; it could be as soon as the beginning of next month, and it could offer him a chance to name a chief justice. With even one appointment he could reshape the court and, in turn, could set in motion forces that could reshape American life. He believes that. Just as important, his opponents believe that.

It’s a recipe for the greatest and gravest political fight of the new millennium. On one side will be activists craving for the chance to shift the two great balances in American life, one between church and state, the other between Washington and the states. On the other will be activists just as determined not to let that happen. A sleepy capital and country will swiftly awaken with passion – and with the insight that any president who can so easily adjust the balance of power in American life still possesses power aplenty himself.