Mark Penn, Burson-Marsteller CEO and advisor to Bill and Hillary Clinton, is among politicos who believes Sarah Palin will not only run for president but have a “high likelihood of winning,” if the economy fails to recover and President Obama doesn’t get his act together.

That’s quite a turnaround from the smug attitude once held by Democratic establishment politicians who, pre-Tea Party madness, drooled over the prospects of a Palin candidacy.

Penn’s solution for Obama -- “moving to the center” a la Bill Clinton -- is not exactly music to the ears of the president's “progressive base.” Penn is among experts quoted in the new issue of New York magazine that features “President Palin” on the cover. It's not a pretty picture.

The haunting specter of a Palin presidency combined with a shaky sitting commander-in-chief could entice an independent run by New York Mayor Michael Bloomberg backed by a $3B personal war chest. Bloomberg’s common sense adult view of the world, financial acumen plus liberal stands on social issues (gay marriage, near-the-World Trade Center mosque) could attract voters turned off by Obama’s failure to deliver important promised goods (“closure” on Iran and Afghanistan comes immediately to mind) and general spinlessness.

A Bloomberg run seriously upends the apple cart. New York’s political writer John Heilemann predicts a solid 40 percent of Democrats will stick with the president, while Palin can count on about 30 percent of the hard-core GOPers. Bloomberg picks up independents, lefty Dems and the few remaining moderate Republicans. Obama gets another four years.

Scenario No. 2: Bloomberg wins New York, California, Florida, New Jersey and Connecticut and edges Obama in some Midwest states. Palin nails the South to deny the President a win in the Electoral College. The race gets tossed into Republican-controlled House of Representatives and the pride of Alaska becomes America’s first female President.

Veteran GOP consultant Mark McKinnon offers a third way. Palin is so hot she becomes a “supernova.” Said McKinnon in New York: “The only parallel is Barack Obama. And look what happened to him.”

My question: Will Sarah flame out before Election Day 2012?

That could put Bloomie in the White House, powered by a coalition of disaffected progressives and anti-Obama fanatics who vote for New York City’s Mayor to shake up the status quo. Crazier things have happened.