WASHINGTON — When Senator Obama released his detailed tax plan, he turned for public support to one of the Democratic Party’s most respected economic voices: Lawrence Summers.

In one of his first appearances as a campaign surrogate, the former Treasury secretary last week touted Mr. Obama’s proposals and rebutted charges from Republicans that his plan for tax and spending increases would damage the economy.

Mr. Summers’s participation on the conference call drew little notice, and that was fine by the Obama campaign. In the two years since he resigned as president of Harvard amid a faculty revolt, Mr. Summers has made a relatively seamless transition back into the upper ranks of Democratic economic scholars.

But in a political environment where sensitivities surrounding race and gender have rarely seemed more acute, it remains to be seen whether Mr. Summers’s widely criticized remarks about women at Harvard will hamper his chances for a Cabinet-level appointment.

Some women are already warning Mr. Obama against giving Mr. Summers a high-profile role during the campaign, particularly as he tries to close the deal with supporters of Senator Clinton who have yet to embrace his candidacy.

His time at Harvard was marked by frequent clashes with professors, none more explosive than after he suggested at an academic conference in 2005 that innate differences may be a reason why fewer women than men excelled in the fields of math and science. Amid a firestorm of criticism, he apologized to the university and said his remarks were a “serious mistake.”

The furor over his comments and other complaints about his leadership led to a vote of “no confidence” by the faculty, and he stepped down in 2006. Despite the cloud surrounding his presidency at Harvard, Democratic leaders have welcomed his return to economic scholarship with open arms, and party economists say he could be on the short list for a top position in an Obama administration, including what would be his second stint as Treasury chief or even as the chairman of the Federal Reserve.

The possibility does not sit well with some female supporters.

“If Obama is trying to court women, particularly women from Hillary’s camp, he should be wary of using Larry Summers as a surrogate. It would potentially cause concerns and hesitation,” the vice chairwoman of the National Council of Women’s Organizations, Shireen Mitchell, said. “It’s a concern that Obama needs to take seriously.”

Mr. Summers’s involvement is also problematic for the contingent of Clinton loyalists who argue that Mr. Obama has not done enough to address women’s issues. “Certainly there are better people in the party and for him to surround himself with who don’t have a negative attitude toward women and their abilities,” the head of the New York chapter of the National Organization for Women, Marcia Pappas, said, adding that theories that women were genetically inferior to men “are the same antiquated views that people had about African Americans.” NOW’s leadership in Washington — which endorsed Mrs. Clinton in the primary but has not criticized Mr. Obama as loudly as the New York chapter — had called for Mr. Summers to resign immediately after his comments; the organization’s national president, Kim Gandy, did not return calls for comment.

Mr. Summers has his share of key allies in Washington that vouch for his scholarship, chief among them the speaker of the House, Nancy Pelosi, who featured him in a Capitol Hill forum last month and highlighted his backing of a second economic stimulus package.

In a statement to The New York Sun, Mrs. Pelosi lauded Mr. Summers as “one of America’s leading economic minds” and all but endorsed an appointment for him in an Obama administration. “I am confident that if Senator Obama chooses to include Mr. Summers in his administration, he will work tirelessly to reverse the failed economic policies of the past eight years, and we will all benefit from his service to our country,” the speaker said.

Supporters say Mr. Summers’s comments at Harvard obscured a strong record on issues related to women. He appointed the first woman dean of Harvard Law School, Elena Kagan, and long before that, as chief economist at the World Bank, he pushed aggressively for increased investment in the education of girls in developing countries.

“The large majority of progressives, myself included, think his comment was a real mistake, that he apologized, and recognize that he has been and remains as an important champion for many progressive issues,” a former director of the National Economic Council in the Clinton administration, Gene Sperling, said in an interview.

Mr. Sperling, who served as chief economic adviser to Senator Clinton’s campaign and now advises Mr. Obama, said he expected that Mr. Summers would have the kind of allies needed to weather a political storm if critics bring up his Harvard comments in a nomination battle.

“The highest elected woman in the history of our country regularly relies on him. That’s got to count for something,” Mr. Sperling said, referring to Mrs. Pelosi.

Ms. Pappas, however, rejected the notion that Mrs. Pelosi would be able to silence criticism from women. “If Nancy Pelosi supports an individual who touts the antiquated idea that women are second-class citizens because of their gender, all I can say is shame on you Nancy Pelosi,” she said.

Mr. Summers may also draw support from people who disagreed with his comment but felt he was treated unfairly at Harvard merely for advancing a provocative idea — a practice they argued should be at the heart of a vibrant academic community.

“He is a big believer and proponent of women, and I think that is why he was talking about the subject in the first place,” a former chief of staff under Mr. Summers at the Treasury Department who now serves as chief operating officer of Facebook, Sheryl Sandberg, said. Ms. Sandberg, a Harvard graduate who studied under Mr. Summers, said he was instrumental in helping her start a student group for women in economics and government.

Mr. Summers, in a brief telephone interview, declined to respond to the concerns women expressed about his role in the campaign. “I’ve just been happy to help the campaign when my advice has been sought,” he said.

When asked about serving in an Obama administration, he replied: “I’m very happy doing what I’m doing now.”

The Obama campaign’s policy director, Heather Higginbottom, said in a statement that the Illinois senator listens to advice from “a variety” of scholars and noted that Mr. Summers is a leading expert on progressive taxation and the current financial crisis. “Dr. Summers has repeatedly said that his comment on women in science was a mistake, and we take him at his word,” she said. “But women are more interested in the fact that Barack Obama has a comprehensive economic agenda for working women while John McCain has opposed legislation to guarantee equal pay and provides little tax relief for America’s working women and their families.”

Despite persistent criticism from a group of vocal Clinton supporters, the Obama campaign has pushed back aggressively against the perception that he has ground to make up with women voters. Polls have consistently showed him leading among women, with a recent Pew survey giving him a 13-point advantage over Senator McCain, 51% to 38%. The gap is greater than the edge either Vice President Gore or Senator Kerry enjoyed over President Bush in the last two elections.

Mr. McCain has his own potential vulnerabilities among the female electorate, largely attributable to a bawdy sense of humor that has occasionally gotten him in trouble over the years. He reportedly told a joke about rape in the 1980s and made a disparaging crack about Chelsea Clinton when her father was president. More recently, he raised eyebrows this month when, during an appearance at the Sturgis motorcycle rally in South Dakota, he quipped that his wife Cindy should enter the annual beauty pageant. The problem: Women in the contest usually compete topless, though it was not clear that Mr. McCain knew that.

As for Mr. Summers, whether his involvement in the Obama campaign becomes a political liability for the Democrat could depend on the reaction of his critics at Harvard. The professor who introduced the “no confidence” resolution at Harvard, J. Lorand Matory, said he was keeping an open mind. “I would not wish to pre-judge Mr. Summers’s contributions, because we all live and learn,” he said.