) --

JPMorgan Chase

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continues to have difficulty getting struggling borrowers eligible for home mortgage modifications to provide the required documents needed to make the changes permanent.

As the trial periods for many modifications expire, JPMorgan Chase and others, including

Bank of America

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, say that it's been tough sledding to get the full documentation needed by the government from borrowers.

For its part, JPMorgan Chase has extended trial offers to struggling homeowners to modify loan terms on more than $100 billion worth of loans this year, the company said Tuesday.

The company said some 568,500 of its mortgages have been given modified terms this year, whether through the Obama administration's Making Homes Affordable program and other government initiatives or through Chase's internal modification programs. But just 83,000 of those modifications have been made permanent (another 112,000 of which are currently approved for permanent changes), Chase says.

Borrowers have been reluctant to provide the documents necessary to complete the process.

"We continue to work very hard to convert customers from a trial modification to a permanent modification that lowers their monthly payment, but it has been a struggle," Charlie Scharf, JPMorgan Chase's head of retail financial services said in a statement.

Scharf also reiterated comments made a month ago at an investor conference, in which he said that

JPMorgan Chase's

loan portfolio could decline by $50 billion, or as much as 15%, as the institution works to unwind troubled mortgages and home equity from its books.

Other big banks including


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, Bank of America through its purchase of Countrywide and

Wells Fargo

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through its purchase of Wachovia are also working to extend modifications to troubled borrowers.

Under the Obama program, borrowers must make at least three trial payments, provide full financial documentation -- including proof of income and hardship verification -- and have their credit re-underwritten to get a permanent modification.

Of the borrowers offered trial modifications from April through September through the Obama program, only about 20% of borrowers have made all payments and provided all the necessary paperwork, and the majority of them are expected to get permanent modifications soon, Chase says.

The majority of borrowers, while being able to make the required payments, have not provided documents acceptable or necessary under the HAMP guidelines, Chase says. Another 29% have not been able to make the required payments, making them ineligible for a permanent modification under the program.

"We want to give customers every opportunity to make their modifications permanent," Scharf says. "We have hired thousands of employees and expanded our outreach, and we have begun to see some improvement in results. We believe our intensified efforts, plus the heightened awareness of these issues, will help further encourage struggling customers to make every effort to complete their modification."

Shares of JPMorgan Chase were falling 0.7% to $40.95. Bank of America shares were down 2.5% to $15.50.

--Written by Laurie Kulikowski in New York.