This story has been updated.

NASHUA, N.H. — Hillary Rodham Clinton dodged Tuesday when asked by a voter to give a definitive yes or no on whether she would support the proposed Keystone pipeline as president.

"If it’s undecided when I become president, I will answer your question," Clinton told Bruce Blodgett, a software engineer from Amherst, N.H.

That leaves Blodgett and other voters to ponder what Clinton might do, since she supported the pipeline idea when she was secretary of state — before it became a cause celebre for environmentalists and Democratic activists who claim it is unnecessary and dangerous.

"This is President Obama's decision. I'm not going to second-guess him," Clinton said during a question-and-answer session with voters at an elementary school here.

Her position – she says it’s inappropriate to comment since she had a hand in the initial discussions about the Canada-to-U.S. pipeline project – was the same one she has articulated before. But it comes as Clinton is trying to stake a claim as a bold thinker on environmental matters, particularly climate change. And in its finality, the answer appeared to close off the possibility that Clinton would be forced to take a stand on Keystone soon.

"I'm sorry if people want me to," Clinton told reporters after the town hall-style session with voters.

"I'm in a different position than any other candidate. I was there. I put this process together. I oversaw it for four years," Clinton said.

"I've been very clear, and have been consistent, that I do not think it appropriate for me to comment on something that I had official responsibilities for until it is completed, and that I might have official responsibilities for again, so that is where I stand," Clinton said Tuesday.

A senior campaign official later said Clinton's refusal to weigh in now is a deliberate choice that carries a political cost.

"I understand there could be political advantages to weighing in on Keystone," Jennifer Palmieri, the director of communications for the Clinton campaign, said in an e-mail statement. "But given her former role as secretary of state and having been part of the Keystone process, she believes that weighing in now could be disruptive to the process and not responsible to do."

"Having the experience of being a former secretary of state distinguishes her and her candidacy, but it comes with responsibilities that at times can limit her.  But we know that the experience is well worth whatever price she may pay politically," Palmieri said.

Clinton's comments came as polls show her losing ground to Sen. Bernie Sanders (I-Vt.) in New Hampshire and a slide in her favorability ratings. Sanders opposes both Keystone and the TPP.

Sanders noted with some approval the proposals for reduced energy use and increased solar energy production Clinton released Sunday, but said they are not enough.

“It is hard for me to understand how one can be concerned about climate change but not vigorously oppose the Keystone pipeline," Sanders said in remarks distributed by his campaign.

Obama, of course, wants a Democrat to succeed him, and Clinton is the front-runner. He must also answer to Democratic critics who have made the pipeline a test of environmental bona fides.

The matter is expected to be decided before Obama leaves office, and Clinton is clearly hoping it will be. The same is true for the TPP, a trade deal she similarly championed as secretary of state that has become unpopular with liberal voters she is trying to court.

Clinton says she needs to wait to see what is in the final TPP package before deciding whether to support it.

"It's not done," she told reporters.

Those hedges differ completely from Clinton's position on the Iran nuclear deal, which she helped foster at the State Department, encouraged and promoted ahead of its completion this month and fully backs now.

"This is a very important, consequential agreement," that will make the Middle East and the United States safer, Clinton said Tuesday. She said she would "vigorously" adhere to its provisions as president.

Clinton's top campaign policy adviser, Jake Sullivan, was among the Obama administration negotiators long after Clinton left office.

Before the deal was finalized, Clinton had said she supported the negotiations and the U.S. position, though, she said she had doubts about Iran's compliance.

She has not articulated the difference between the Iran program and the two pending proposals that allowed her to weigh in before that deal was done. Like the others, the Iran deal is unpopular with some key constituencies she needs — namely many politically active pro-Israeli Jewish Americans.

Republican National Committee spokeswoman Allison Moore called Clinton's explanation on Keystone "bizarre." In a press release, the RNC pointed to additional instances where the candidate has discussed ongoing foreign policy issues she handled as secretary, such as the Russia "reset" and the war in Syria. The Iran matter is the more pointed comparison, however, because like Keystone or the trade agreement known as the Trans-Pacific Partnership (TPP) if they come to fruition, it is a packaged proposal that carries the administration imprimatur.

Also Tuesday, the chairman of the House Select Committee on Benghazi said it would postpone a hearing scheduled for Wednesday to question Jon Finer, Secretary of State John F. Kerry's chief of staff, in the ongoing political fracas of Clinton's use of private e-mail when she was secretary.

Finer, a former Washington Post reporter, was to testify about what Rep. Trey Gowdy (R-S.C.) called the department's "compliance failures" in turning over e-mails to and from 10 senior Clinton officials during her time in office.

In exchange for the postponement, Gowdy said, State would send the committee approximately 5,000 pages of staff e-mails Wednesday, slightly more than the number handed over last spring.

The staff e-mails, which will not be publicly released, are separate from some 55,000 e-mails from Clinton's private server now being culled by the State Department, which is under court order and committee subpoena to release them.

Clinton has said none of her e-mails contained classified information, but State Department officials later told intelligence officials that potentially "hundreds" included information that should have been classified, but wasn't at the time Clinton e-mailed it. The inspector general of the 16-agency intelligence community later said that his investigators found at least four e-mails with definitely classified material in a selected sample of 40 the State Department allowed them to see, and referred the matter to the Justice Department.

Karen DeYoung contributed to this report.

Correction: Due to an editing error, questioner Bruce Blodgett's residence was incorrectly reported as Amherst, Mass. He lives in Amherst, N.H.