WASHINGTON — The senator overseeing Barack Obama’s swearing-in ceremony is writing to Internet sites like eBay asking them not to sell scalped inauguration tickets.

Senator Dianne Feinstein of California is also writing a bill that would make it a federal crime to scalp tickets to the historic event January 20.

Feinstein, who chairs the Joint Congressional Committee on Inaugural Ceremonies, says she foresees overwhelming demand for the 240,000 available tickets and has heard reports of them being sold for as much as $40,000 online.

The tickets are supposed to be free to the public and distributed through congressional offices. The offices won’t get the tickets until shortly before the inauguration, to try to prevent scalping.