At the Bill, Hillary & Chelsea Clinton Foundation, an intense period of fund-raising is underway, which is widely seen as an effort to build up the family’s charitable operation now, because a presidential campaign would soon interfere with philanthropic activities. A foundation fund-raiser the Clintons threw in the Hamptons in August cost as much as $50,000 per couple to attend.

Last month, Chelsea Clinton resigned from NBC News after less than three years as a special correspondent. In a Facebook message, Ms. Clinton said she stepped down “to continue focusing on my work at the Clinton Foundation” and as she and her husband, Marc Mezvinsky, expect their first child. But she would have likely had to step back from that job should her mother embark on a presidential campaign.

These days Mrs. Clinton’s mind seems to drift to Iowa, as she has been casually asking friends about who’s who in the state’s Democratic Party, said two people who could discuss private conversations only anonymously.

On Sunday, Mrs. Clinton will make her first trip back to Iowa since early 2008, when she came in third in the heated Democratic caucus behind Mr. Obama, then a senator from Illinois, and Mr. Edwards. Mr. and Mrs. Clinton will both attend the steak fry, a fund-raiser in Indianola known as a must-stop for potential presidential candidates.

It has long been an opportunity for presidential candidates “to get out there and dip your toe in the water and introduce yourself to a lot of active Democrats,” said Scott M. Brennan, chairman of the Iowa Democratic Party. (He added that the Clintons were attending to help Democrats in 2014 and to pay tribute to Mr. Harkin, who is retiring from the Senate.)

Back in New York and Washington, Mrs. Clinton has a packed schedule this month to raise money for Democratic candidates; she headlined a reception Friday to benefit the Democratic Governors Association that cost $10,000 to attend. Mr. and Mrs. Clinton are not slowing down on delivering paid speeches, at around $200,000 each. A presidential campaign would limit those opportunities to make money.

Mrs. Clinton is getting in better physical shape, a necessity for any potential candidate who faces the rigors of the campaign trail. Friends said she has more energy and has also been practicing yoga.