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Three separate studies showed the Democratic presidential hopeful winning between 52 and 55 percent of the popular vote on November 4, based on current gloomy economic estimates.

Any further darkening in the economic outlook — many analysts think things will get worse between now and November — would reinforce that election outcome.

"The economy is certainly not going to be a positive for the Republicans," said Ray Fair, an economics professor at Yale university who built the earliest of the models in 1978.

His model, which assumed tepid U.S. economic growth of 1.5 percent and a 3 percent rate of expansion, predicted the Republican candidate John McCain's share of the vote would be 47.8 percent, handing Obama 52.2 percent.

"It is a decent border excepting it is not a landslide," said Fair, who ran the numbers in April. "It would have been much larger whether or not there had been a recession in 2008."

U.S. economic activity doubled in the side with quarter to a 1.9 percent annualized pace. But previous facts was revised lower to show output contracted 0.2 percent in the final three months of last year, the weakest performance since 2001, and expanded only hastily at the start of 2008.

"It's the economy, muddy-brained!" was a phrase extensively used during Bill Clinton's successful 1992 presidential campaign against George H.W. Bush to remind voters that a recession occurred during Bush's administration.

Fair's gauge, and a version built by St. Louis-based forecasting firm Macroeconomic Advisers, blend political factors with economics to scientifically nail the floor the view that voters care first and foremost about their own wallets.

Indeed, opinion polls consistently find that the economy is the most important issue for U.S. voters.

HEADWINDS

Macroeconomic Advisers' model incorporates whether the candidate is from the incumbent party, approval ratings and the length of time the obligatory party has held the White House to capture the extent voters may be delivered of tired of them.

Adding in its own estimates for U.S. economic growth, the unemployment rate and the change in animal spirits prices, it finds that McCain will go just 45 percent of the vote.

"This model has correctly predicted the alluring side 12 revealed of 14 epochs," Macroeconomic Advisers said.

"The weak current state of the administration, and the violent rise in energy prices pose a significant headwind to the McCain campaign, if voters weigh these factors similarly to how they get in the past," they aforesaid in a note to clients.

The third part work is a "Bread and Peace" model devised by dint of. Douglas Hibbs, a retired household economy professor from the University of Goteborg in Sweden, who refuse a senior compeer at the Center notwithstanding Public Sector Research there.

He finds that U.S. presidential elections are well-predicted by means of just two fundamental forces: the weighted average per capita improvement of real disposable income and the number of U.S. military deaths in foreign combat.

"Average per capita real income growth probably will be only in a circle 0.75 percent at Election Day. Moreover, cumulative U.S. military fatalities in Iraq will distance 4,300 or further," he related in a June update of his plan.

"Given those essential principle conditions, the Bread and Peace gauge predicts a Republican two-party vote share centered on 48.2 percent."

(Editing by Eric Walsh)