(Adds details, reaction; Jacksons intend to plead guilty)
By David Ingram and Mary Wisniewski
WASHINGTON/CHICAGO, Feb 15 (Reuters) - Former Chicago congressman Jesse Jackson Jr., son of the famed civil rights leader, plans to plead guilty to charges filed on Friday accusing him of misusing $750,000 in campaign funds, his attorney said.
Jackson's wife, Sandi Jackson, has also agreed to plead guilty to a related charge of filing false tax returns, according to her attorneys. She resigned her seat on the Chicago city council last month.
Both Jacksons, once considered one of the most powerful couples in the city, issued statements accepting responsibility.
"I offer no excuses for my conduct and I fully accept my responsibility for the improper decisions and mistakes I have made," said Jesse Jackson Jr, a Democrat, in his statement. He faces fraud and conspiracy charges.
Jackson's wife said in a statement that she was "deeply sorry" for her actions.
Once considered one of the most promising black politicians in the United States, Jesse Jackson Jr. resigned his congressional seat on Nov. 21 for health reasons, acknowledging at the time that he was under investigation by the FBI.
Jackson was once talked about as having the potential to become the first black president, noted Andy Shaw, president and CEO of the Chicago-based Better Government Association.
"Instead of heading for the White House, he is heading for the big house, and that is an enormous fall from grace," Shaw said in a radio interview on WBBM-AM.
Jackson's father, a former presidential candidate, was not immediately available for comment.
Prosecutors said at least seven people were involved in the scheme to divert campaign funds to personal uses.
Among the accusations is that Jesse Jackson, Jr. shipped a $43,350 men's Rolex watch purchased with campaign funds to his D.C. address. He also shipped fur capes and parkas purchased with $5,150 in campaign funds to the Beverly Hills home of an unnamed person, the documents said.
As part of the case, the government said Jackson must forfeit tens of thousands of dollars in celebrity memorabilia derived from the alleged crimes, including a $4,600 fedora that once belonged to late pop star Michael Jackson.
Under federal sentencing guidelines, if convicted, Jackson faces a maximum penalty of five years in prison and his wife three years, but defendants who accept responsibility are typically sentenced to much less than the maximum term.
Jackson disappeared from public view early in the summer of 2012 and speculation swirled for weeks about his condition. He said in late June he had taken a leave of absence two weeks earlier for treatment of what was then described as exhaustion.
Jackson issued a statement in early July saying his health problems were more serious and he needed extended in-patient treatment for unspecified "physical and emotional ailments."
Days later, his physician said the congressman was receiving intensive care for a "mood disorder" and was expected to make a full recovery. The Mayo Clinic announced in late July that Jackson had been admitted.
He was treated for at least six weeks at Mayo for bipolar disorder, sometimes called manic depression, which is marked by highs and lows of mood and can be treated by medication and psychological counseling.
Representative Danny Davis, another Chicago Democrat, said he believed the alleged offenses were related to the disorder, the symptoms of which can include reckless behavior, such as spending sprees.
"It's kind of beyond one's imagination," Davis told Reuters. "A $5,000 football - that's kind of bizarre. It's so sad and so unfortunate."
Jackson made it to Congress in 1995 after winning a special election triggered by the resignation of Representative Mel Reynolds, who was convicted of sexual assault, obstruction of justice and solicitation of child pornography. Reynolds is now vying for the seat again in a Feb. 26 Democratic primary.
Jackson was a reliable liberal vote during his 17-year House career, supporting increases in the minimum wage, the expansion of environmental regulations and gay rights and, in 2008, the bailout of the teetering U.S. financial system.
He was also an early advocate of a strict timeline for withdrawal of U.S. troops from Iraq. He was easily re-elected in November 2012, despite his absence from the district. His resignation came two weeks after the election.
In addition to the federal investigation of his campaign finances, Jackson had been the subject of a House ethics committee probe over an alleged bribe offered by a Jackson supporter in 2008 to then-Illinois Governor Rod Blagojevich.
The bribe was said to be intended to entice Blagojevich to appoint Jackson to the U.S. Senate seat vacated by President Barack Obama. Jackson has admitted to lobbying for the seat, but denied knowing about any money offered to Blagojevich, who has since been convicted of corruption and imprisoned. (Reporting by David Ingram in Washington, D.C., and Mary Wisniewski in Chicago; Editing by David Brunnstrom)