WASHINGTON â The House ethics committee is expanding an investigation of Rep. Charles Rangel, chairman of the tax-writing Ways and Means Committee. The ethics panel issued a statement Tuesday saying it had voted to expand an already far-ranging probe into the New York Democrat to examine whether he protected an oil drilling company from a big tax bill when the head of that company pledged a $1 million donation to a college center named after the congressman. The move means the Rangel inquiry will likely stretch well past early January, when House Speaker Nancy Pelosi, D-Calif., had previously said she expected the matter to be resolved. Republicans have called for Rangel to step down from his chairmanship of the powerful Ways and Means panel during the investigation. The expanding investigation means the ethics cloud hanging over Rangel is likely to follow him and Democratic leaders into the next Congress as they seek to pass major stimulus legislation and buoy the sinking economy. The committee will now investigate contributions or pledges of money made to the Charles B. Rangel Center for Public Service at the City College of New York, particularly one made by Eugene M. Isenberg, CEO of Nabors Industries, Ltd. Rangel, 78, reportedly helped preserve a tax loophole that saved the company tens of millions of dollars a year. The congressman, who has been in office for 40 years, maintains he has done nothing improper, and he says he has always opposed the kind of change to tax law that would have cost Nabors dearly. The ethics committee said it was expanding the probe after Rangel asked them to do so. The committee has already been probing Rangel's failure to pay taxes on about $75,000 in rental income from a beach house he owns in the Dominican Republic. They are also eyeing his use of three rent-stabilized apartments in Harlem, including one for a campaign office. Also under scrutiny are letters Rangel wrote on congressional stationery looking to drum up donors for the college center. College officials have refused to say who donated to the Rangel center, citing the ongoing investigation. Rangel has insisted that whatever he did wrong, they were honest mistakes, not intentional deceptions.