The New York Times, citing two Republicans close to McMahon, says she is seeking the Republican nomination for the seat now held by Joe Lieberman. Lieberman, a Democrat turned independent, is retiring after four terms.
McMahon spent $50 million of her own money last year, winning the Republican nomination and losing to the state attorney general, Richard Blumenthal. Critics last year suggested McMahon was trying to use her wealth to buy a Senate seat, and the Times' sources said she plans to seek donations in her new campaign.
Connecticut is a generally liberal state where the Democratic Party now has a strong advantage. Christopher Shays, a moderate who was the last Republican from New England in the House until his loss in 2008, is believed to be considering a run for the Senate.
On the Democratic side, former Secretary of State Susan Bysiewicz, Rep. Christopher S. Murphy and William Tong, a member of the state Legislature, are running for the nomination.