WASHINGTON — A day after her nomination ran into trouble in the Senate, President Obama’s pick to head the Social Security Administration passionately defended her integrity, her long career in government and her handling of a troubled computer project she inherited from a predecessor.

“I’ve always met the highest ethical standards,” Carolyn W. Colvin told The Associated Press in an interview Thursday. “I’ve worked in government my entire life. There’s never been a suggestion, personal or professional, of any wrongdoing.”

“I’m certainly not ending my career with that,” Colvin continued. “I came out of retirement to help this organization, not hurt it.”

Obama nominated Colvin to a six-year term as commissioner of the agency in June. She has been acting commissioner since February 2013. Before that, she had been the agency’s deputy commissioner since 2010.

A group of Republican senators plans to try to block Colvin’s nomination while investigators look into a $300 million computer project that doesn’t work. In a letter to Colvin, all 11 Republicans on the Senate Finance Committee said there is evidence that Social Security officials have misled Congress and investigators about problems with the project.

The senators wrote that they can’t let a nomination proceed to a vote “as long as the specter of a potential criminal investigation surrounds the nominee,” that person’s inner circle, or both. Sen. Orrin Hatch of Utah, top Republican on the Finance Committee, leads the group.

The White House said Thursday that the president believes Colvin deserves a confirmation vote by the full Senate.

Six years ago, Social Security embarked on an aggressive plan to replace outdated computer systems that were overwhelmed by a flood of disability claims. But the project has been racked by delays and mismanagement, according to an assessment commissioned by the agency over the summer.

The project is still in the testing phase and the agency can’t say when it will be operational or how much it will cost.

Social Security’s inspector general started investigating the project in the summer. The IG said in a report that investigators attended numerous briefings on the computer project, including two this year, but the Social Security Administration “never indicated it was experiencing significant problems with the project.”

The investigation has since been turned over to the inspector general for the Small Business Administration to avoid a potential conflict of interest.

Colvin noted that the project was launched “way before I got here,” under former Commissioner Michael Astrue. Colvin said she has been working to salvage it since she took over the agency last year.

“That’s what I do, I’m a problem-fixer,” Colvin said. “Every organization I’ve gone into I try to identify what the vulnerabilities are and try to fix them.”

Colvin, however, said Thursday she does not know whether the computer project can be saved, even though the agency has spent nearly $300 million on it.

During an interview in her Washington office, Colvin said she was reluctant to talk about the project because of the ongoing investigation. The interview had been scheduled to discuss the agency’s efforts to fight fraud, but Colvin answered a few questions about her nomination.

Colvin was adamant that she did not know of anyone in the agency misleading Congress or investigators.

“Certainly I don’t know of anyone,” Colvin said. “I haven’t been interviewed or given specifics, and I think that it would be inappropriate for me to say a whole lot more.”

Colvin said she first learned about problems with the project after she took over as acting commissioner. She said overseeing the project was not part of her duties as deputy commissioner.

Colvin, 72, first worked as a deputy commissioner at Social Security in the 1990s. She left the agency in 2001 to become director of human services for the District of Columbia. She later had a similar job in Montgomery County, Maryland.

The Associated Press first reported about problems with the computer system in July.

The Senate Finance Committee advanced Colvin’s nomination as Social Security commissioner to the full Senate in September. The vote was 22-2, and her nomination seemed to be assured.

“Sen. Hatch was aware of this when I had my confirmation hearing,” Colvin said of the project. “He alluded to it but he didn’t ask questions, so I assumed that everything was resolved.”

This week, Finance Committee Chairman Ron Wyden, D-Ore., said a vote on Colvin’s nomination should be delayed until she answers questions about the project, increasing the likelihood that a vote will be pushed into next year, when Republicans take control of the Senate.

Colvin said the project “is something that I am very concerned about. It’s something that we’re certainly going to be very forthright and forthcoming in answering the questions of Congress and we’re going to let the investigation take its due process.”