While the ultimate occupants of three United States Senate seats are yet to be determined in Alaska, Georgia and Minnesota, chances seem small that Democrats will increase their new majority to 60 seats — the supermajority that ensures against a successful filibuster. So the same Republicans who once complained about the use of that legislative weapon by the opposition now brandish it in warning to President-elect Barack Obama.

Nobody can doubt that the Republican remnant in the Senate will obstruct as soon as that seems politically safe. Right-wing pundits, from Rush Limbaugh to the Wall Street Journal editorial page are already egging them on furiously. But is there enough muscle behind that filibuster threat to block Obama's mandate?

The short answer is no — and the new president's own political arsenal should enable him to call the Republican bluff.

Let's count the actual votes on the Republican side of the aisle, asking which senators would have both the inclination and the will to join a filibuster. Every issue calls forth different levels of resistance, of course, but in each instance the opposition would need at least 41 total. In the very worst case, should the Republicans pick up all the remaining seats, they will begin with three more than that.

Six Senate Republicans will face reelection two years hence in states that went for Obama: Judd Gregg (R-NH), Arlen Specter (R-PA), George Voinovich (R-OH), Mel Martinez (R-FL), Chuck Grassley (R-IA) and Richard Burr (R-NC). Having seen their fellow incumbents fall in the last two elections, that half dozen may well consider themselves in varying degrees of political peril. Poor Gregg watched his New Hampshire colleague John Sununu drop this year as their state turned deep blue. Martinez won his seat in 2004 by a single point and is widely considered vulnerable. So are Specter, nearing his 80th birthday, and Voinovich, now 72.

Several other Republican incumbents may confront difficult reelection races in 2010, too, including Kit Bond (R-MO), whose state went for John McCain by a miniscule margin (many votes fewer than the number who voted for Ralph Nader). Nor should we forget Jim Bunning (R-KY), 77 years old and aging badly, who was nearly taken out in 2004 by an underfunded, little known Democrat. Recent polls show him sinking.

And finally there is McCain himself, whose popularity in Arizona has diminished markedly this year. His term will expire in two years as well, and at least one poll shows that he would lose his seat to Janet Napolitano, the state's popular Democratic governor. Perhaps that is why he returned home to campaign on the eve of the election.

As the nation rebalances its politics away from the right, Senate Republicans may well ask whether they can maintain even their diminished numbers in the next cycle. How eager will any of these endangered incumbents be to participate in filibusters that will leave them open to the "obstructionist" label that Republicans used to slap on Democrats who fought the Bush administration?

The matter of incumbents and filibusters seems highly relevant to another problem that the new president must solve. What will he do with the remarkable political machine created by the Obama campaign?

Filibuster prevention would be a worthwhile and inspiring project for those idealistic millions. Early next year, the president-elect and his new Democratic Party chair can start to deploy those massive resources into sweetening the Senate. They can mobilize the grassroots and the netroots in the 2010 Senate states — and across the country — to keep pressure on Republican incumbents while building support for their potential challengers.

Such a scenario presumes, of course, that the president-elect is determined to enact the promise of change rather than placate the opposition. So far there is no reason to presume otherwise — and that is why he must prepare for the worst.

Joe Conason writes for the New York Observer (www.observer.com). To find out more about Joe Conason, visit the Creators Syndicate website at www.creators.com.

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