Encouraged by a group of influential New York Democrats, Harold Ford Jr., the former congressman from Tennessee, is weighing a bid to unseat Senator Kirsten E. Gillibrand in this fall’s Democratic primary, according to three people who have spoken with him.

Mr. Ford, 39, who moved to New York three years ago, has told friends that he will decide whether to run in the next 45 days. The discussions between Mr. Ford and top Democratic donors reflect the dissatisfaction of some prominent party members with Ms. Gillibrand, who has yet to win over key constituencies, especially in New York City.

About a dozen high-profile Democrats have expressed interest in backing a candidacy by Mr. Ford, including the financier Steven Rattner, who, along with his wife, Maureen White, has been among the country’s most prolific Democratic fund-raisers.

“Maureen and I worked hard for Harold in his last race because we think the world of him,” Mr. Rattner said, referring to Mr. Ford’s run for the Senate in Tennessee in 2006. “He has extraordinary drive and intelligence and will excel at anything that he chooses to do.”

Among those who have encouraged Mr. Ford to consider a run are Merryl H. Tisch, the chancellor of the New York State Board of Regents, whose husband, James, is the chief executive of the Loews Corporation, and Richard Plepler, the co-president of HBO, according to people who have spoken with them.

Mayor Michael R. Bloomberg, who has publicly tangled with Ms. Gillibrand, is open to the possibility of supporting a challenger of Mr. Ford’s stature, according to those familiar with his thinking.

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In New York, Mr. Ford took a job as vice chairman of Merrill Lynch, where he cultivated close ties to many of the Wall Street executives who are now encouraging him to run. A telegenic politician, he has also maintained a high profile through NBC and MSNBC, which feature him as a regular political commentator.

Embattled Connecticut Sen. Chris Dodd (D) has scheduled a press conference at his home in Connecticut Wednesday at which he is expected to announce he will not seek re-election, according to sources familiar with his plans.

Dodd's retirement comes after months of speculation about his political future, and amid faltering polling numbers and a growing sense among the Democratic establishment that he could not win a sixth term.

It also comes less than 24 hours after Sen. Byron Dorgan (D-N.D.) announced he would not seek re-election.

State Attorney General Richard Blumenthal is widely expected to step into the void filled by Dodd and, at least at first blush, should drastically increase Democrats' chances of holding the seat.