Not so long ago the talk was all about the self-perpetuating machine the Republicans were constructing in Washington.

The image was of links in a chain of power that the Democrats could never break. The GOP, having captured both houses of Congress and the White House, could press lobbyists to hire only Republicans and give money only to Republicans. The money would guarantee dominance in state legislatures. The legislatures would redraw congressional districts so that Democrats could never win. And if anyone objected, too bad; Republican-appointed judges could be counted on to slap down any complainers.

All in all, a perfect loop. Even when House Majority Leader Tom DeLay was indicted in September, he was depicted as a no-longer-essential cog in the apparatus he had helped design and build. People could come and go, the chain would remain.

The mood in Washington today is different. It's been remembered that the chain holds only as long as most people vote next year the way they voted last year.

Today it is conceivable, though by no means assured, that Democrats' vote total in 2006 could grow, and Republicans' shrink, by enough to shift control of the House or Senate. Even a whiff of such uncertainty may prompt donors to hedge their bets.

It may seem obvious, but the distinction between what the Republicans have created and a government truly impervious to public sentiment is worth noting. After all, there are regimes -- in Russia, for example -- that so pervert the forms of democracy that they insulate themselves from changes in public sentiment, unless those are drastic or somehow expressed outside the law. That's not where we are. A healthy dose of cynicism about the goings-on here is appropriate; an overdose of cynicism is not.

This doesn't mean the analysis of Republican ambitions was wrong. Much of it was right, and much of what the Republicans have done -- their Texas redistricting, for example -- merits all the contempt that it has engendered, and more.

Norman J. Ornstein, an expert on Congress at the American Enterprise Institute, says that a shift in public sentiment comparable to the one that swept Republicans into the House majority in 1994, with a gain of more than 50 seats, would produce a shift of only 20 or so seats for Democrats today. That would be enough to unhorse the Republicans, but barely. And that's in large part because Republicans have given themselves larger cushions in nominally competitive districts, he says. So the House, which was designed to be most responsive to public opinion, may now be less responsive than the Senate.

"There's no such thing as a perfect machine," he said. "But they have built in a lot of advantages, and Texas may have made the difference."

But the imperfections are increasingly visible. Some are internal: the arrogance, greed and complacency that swell with time in office, and the disparate interests of supporters that become harder to paper over. Drug companies, seniors' lobbies and chambers of commerce may all support you, but they also may have different ideas of the proper design and cost of a Medicare drug benefit. The result may make no one happy.

There are external stresses, too. Unlike in Russia, it turns out that prosecutors and judges can't be controlled, no matter who appoints them: just ask DeLay, Jack Abramoff or Scooter Libby. Unlike in Russia, neither can the press. The congressional Republicans' cringing abdication of their branch's traditional oversight role has helped diminish attention to scandal and malfeasance, but it can't erase bad news altogether.

And unlike in many pseudo-democracies, the mechanics of elections, including, not least, the counting, can't be controlled by those in power -- which means that they do need to worry about what voters think.

None of this guarantees that the Democrats will win next year. But it does mean their fate isn't entirely out of their hands; much will depend on them -- on the policies they develop, the candidates they recruit. The machine isn't indestructible.