It is a small apartment in a scrubby section of Jamaica, Queens, where the average household income is $33,800 and many residents receive government assistance.


But from this unlikely address, nearly $900,000 has flowed to the campaign accounts of powerful political players across the country.


It is hard to say where the big sums are coming from.


Neighbors describe the man who lives inside — James Robert Williams, 64 — as a reclusive figure who walks with a cane and orders Chinese food for many of his meals.


Yet Mr. Williams, who has few apparent assets and no obvious source of income, has become a major benefactor to political candidates and risen to V.I.P. status in New York Republican circles.


He was recently named by Edward F. Cox, the state Republican Party chairman, to serve on an advisory panel that featured party notables, including a former White House spokesman and a former New York secretary of state.


And he was honored in 2009 as “corporate citizen of the year” during an event at the Grand Hyatt New York in Midtown, where he shared the dais with Mitt Romney, now the presumptive Republican presidential nominee.


But Mr. Williams, who contributed to more than 50 campaigns in the past five years, appears to be bipartisan. In addition to the $400,000 he and companies listed at his address gave to Republican state and county committees in New York, he contributed $50,000 to Andrew M. Cuomo’s campaign for governor, and $20,800 to another Democrat, Representative Charles B. Rangel.


Among the Republican lawmakers and groups who received contributions were Senator John McCain, $57,800, for his presidential run; the Republican National Committee, $31,250; and Representative Eric Cantor of Virginia, $10,000. The bulk of the money was given between 2008 and 2011.


“The guy is unbelievable,” said Joseph J. Savino, the Republican Party chairman in the Bronx, which received an $8,000 donation. “He’s great.”


Still, there is much that is mysterious about James Robert Williams, who also goes by J. R. Williams, Bob Williams and Robert Williams.


According to documents at the New York Department of State, Mr. Williams has formed at least 25 companies, most of them based at his apartment on 170th Street in Jamaica. But there is little evidence of their existing beyond incorporation papers, and most are now inactive.


Records also show he described himself as a lawyer, though the school he says he attended — Indiana University — has no record of it. The law firm he indicated he worked for says it never employed him.


And despite the donations he has showered on politicians of both parties, those who have received the contributions say they have little idea of how he makes his money.


The New York Times asked Republican Party officials how Mr. Williams was selected for appointment to the panel by Mr. Cox, known as the Chairman’s Advisory Council, and for the honor of corporate citizen.


The state party referred a reporter to a public relations representative for Mr. Williams. But the representative said he could not answer questions about Mr. Williams, or be of any assistance, because Mr. Williams had disappeared after learning of the reporter’s interest.


“Mr. Williams has become completely unreachable,” Andrew Moesel of Scheinkopf Ltd., the public relations firm, wrote in an e-mail. “If he ever does emerge and contact us, you will be the first to know.”


Becky Miller, a party spokeswoman, later sent an e-mail saying, “Bob Williams is one of several men and women from all walks of life and every corner of the state who provide support and guidance to the New York State Republican Committee.”


Before he vanished, Mr. Williams rebuffed a reporter who went to his apartment building and tried to ask him some basic biographical questions, like where he went to school. Mr. Williams said the questions were “more complicated” than they seemed and ended the conversation over a phone in the building’s lobby.