* Cut is from 35 percent
* Proposal is Obama's first foray into tax reform
* Analysts see remote chance of election year action
By Kim Dixon
WASHINGTON, Feb 22 (Reuters) - The Obama administration on Wednesday will propose cutting the top tax rate for corporations to 28 percent, and pay for it by eliminating dozens of tax loopholes companies now use to lower their rates, a senior administration official said.
Most analysts doubt that the convoluted tax system could be revamped by a deeply divided Congress in an election year, but the announcement is certain to fuel debate in the run-up to November's elections.
The plan, over a year in the making, is President Barack Obama's first official foray into reform of the tax code, which most experts believe badly needs a revamp after years of being loaded up with special provisions.
The centerpiece is a cut in the top corporate rate - now at 35 percent, among the highest in the industrialized world. That will appeal to businesses, which gripe that the current U.S. rate puts them at a competitive disadvantage.
Controversy will erupt when officials lay out which "loopholes" they want to cut.
The proposal makes a special carve-out for manufacturing - cutting that tax rate to 25 percent - and proposes a minimum tax on profits earned in low tax countries.
Administration officials told reporters on Tuesday the Treasury Department would put out a corporate tax reform plan on Wednesday. The Obama plan will follow such principles as "fairness" that the president set out in his State of the Union address to Congress last month, the officials said.
After the presidential and congressional contests are decided in November, a number of major tax and budget issues will converge on Washington and new momentum for comprehensive tax reform may follow.
Treasury Secretary Timothy Geithner told a Senate committee last week that "dozens and dozens" of tax loopholes were being targeted for closure, but that some tax incentives would be kept for "creating and building stuff in the United States."
Potomac Research analyst Greg Valliere said: "Even if Geithner floats something and members of both parties say they're interested, I simply cannot see a reform bill passing before the election, close to a zero percent chance."
He added: "I suppose anything would be possible in a lame-duck session in December, but something this huge and complex will require a thorough vetting, and that could take a year - or much longer." A lame-duck session would come after the election, but before the next Congress, with newly-elected members, convenes in January.
The last major rewrite of the tax code came in 1986 under Republican President Ronald Reagan, who raised corporate taxes. Talk of tax reform has dominated the presidential campaign.
Republican presidential candidate Mitt Romney on Tuesday called for a flatter, fairer and simpler tax code. He is scheduled to make a major economic speech on Friday in Detroit. Details of his tax plan may emerge before then.
Corporations are clamoring for a cut in the top rate of 35 percent. While that level is one of the world's highest, few U.S. corporations actually pay it due to assorted loopholes that make their effective tax rates lower.
"Everyone agrees on the basic principle of lowering rates in exchange for eliminating loopholes," said Dean Baker, co-director of the Center for Economic and Policy Research, a think tank.
"However, I think it is important that the target be some increase in tax revenue. While we are at the top in marginal tax rates ... we rank near the bottom in effective average taxation."
Republican Representative Dave Camp, chairman of the U.S. House of Representatives tax-law writing Ways and Means Committee, wants to slash the top corporate rate to 25 percent.
Obama last week unveiled a $3.8 trillion budget-and-tax proposal that called for aggressive government spending to boost the economy and for higher taxes on the rich.
On Friday, Congress approved extending a payroll tax cut through the end of 2012. Its expiration will coincide with several other fiscal earthquakes: the expirations of individual tax cuts enacted under President George W. Bush, and $1.2 trillion in automatic budget cuts across all government programs imposed as part of last year's deal to raise the debt ceiling.
After these events and others, analysts said, thorough tax reform may be a realistic prospect. For now, they said, tax proposals will largely amount to political messaging.