Over holiday drinks, a senior Republican offered this tasty tidbit: Mike Bloomberg, the zillionaire mayor of New York City, is still serious about running as a third-party candidate for president next year. His plan: Wait until after the early primaries, see who emerges, and then decide if there’s room for an insurgent campaign.

Normally, we would dismiss this as cocktail chatter. Bloomberg is a shrewd investor, and the chances of him plunging ahead — and betting millions on a very long shot — remain quite slim.

Still. Our source is well connected. Bloomberg refuses to rule out a bid. And the candidates already in the race insist on saying inane things that make voters unhappy and increase their openness to a third option.

Bloomberg loves publicity, and his recent stunt — having breakfast in a New York deli with Barack Obama — fed his ego more than his stomach. But he does understand that many Americans are truly sick of the paralysis in Washington and the game playing on the campaign trail.

He was on the money when he told CBS: “This country doesn’t need somebody that’s going to say, ‘my party versus your party.’ This country needs somebody that says, ‘I’m going to get the best from both parties.’”

Instead, the debate in both parties has turned nasty and silly. The prize for the most ridiculous comment goes to Hillary Clinton, who must be freaking out over poll numbers that show Obama pulling ahead in Iowa. Her campaign attacked Obama’s assertion that he had never dreamed of a White House bid. The evidence: “In kindergarten, Sen. Obama wrote an essay titled ‘I Want to Become President.’”

Sure, Obama instigated the negative exchange by challenging Clinton’s votes on Iran and Iraq. But at least those happened within the past 40 years. On what planet does a childhood exercise prove that an adult’s statements are “fundamentally at odds” with the truth (as a Clinton spokesman put it)? Bloomberg must have ordered more campaign buttons when he read that whopper. (Clinton should be grateful for the writers’ strike — Leno and Letterman would be killing her.)

Like Clinton, Mitt Romney has been spooked by polls in Iowa, which now put Mike Huckabee ahead. Romney’s reaction: Brand Huckabee, the former Arkansas governor, as a “wild-eyed spendthrift,” in the words of The New York Times.

But the Times, in a detailed assessment of Huckabee’s record, called Romney’s charge “hardly apt.” The truth is that any taxes raised during Huckabee’s tenure had strong bipartisan support. Some financed key improvements, such as roads; the courts or the state constitution mandated others. Romney, a former governor, knows all that, but he ignores reality for political purposes. At least he doesn’t accuse Huckabee of raising taxes on his kindergarten class.

Meanwhile, Congress is dumping fuel on the fire of voter disenchantment. Lawmakers have passed only one of 12 bills needed to finance the government. Legislative efforts to deal with critical problems — from undocumented workers to uninsured children — have failed miserably.

Which gets us back to Bloomberg. In this climate, his message of pragmatic efficiency would find a ready audience. He’s right that voters want “the best from both parties.” Translating attitude into action, however, will be very difficult.

Unlike countries with parliamentary systems, American politics is rigged against third parties. We have one party and one president in power at a time. No coalitions. (And that’s a good thing; this country is too big and diverse to tolerate an array of splinter parties.) In 1992, Ross Perot received 19 percent of the vote but ended up with nothing — no cabinet post, no Congressional seat. In 1998, Germany’s Green Party got 6.7 percent and earned 47 places in parliament and three cabinet slots.

Moreover, successful third-party candidates in America have always needed a strong regional base (George Wallace carried five Southern states in 1968) or a strong central theme (Perot emphasized fiscal responsibility). Bloomberg has no geographical stronghold, and he espouses a philosophy, not a program.

But a well-financed organization, Unity ‘08, is already working to ensure places on state ballots for a third-party drive and plans to hold an Internet convention to pick a nominee next summer. One founder, Doug Bailey, sounded a lot like Bloomberg when he told columnist David Broder last winter: “The partisan bickering in Washington continues nonstop, and the contest for the nomination in both parties is likely to make it worse.”

That prediction proved accurate. And that’s why the door for Bloomberg is still slightly open.

(Steve Roberts’ latest book is “My Fathers’ Houses: Memoir of a Family” (William Morrow, 2005). Steve and Cokie Roberts can be contacted by e-mail at stevecokie@gmail.com.)