WASHINGTON (Reuters) - Democratic presidential candidate Hillary Clinton said on Friday she was sorry that her use of a personal email account while secretary of state had caused confusion, and blamed herself for “not thinking a lot” about the matter when she took the job.

Democratic presidential candidate Hillary Clinton speaks during a press conference after talking about her strategy for rural America during a campaign stop at the FFA Enrichment Center at Des Moines Area Community College in Ankeny, Iowa August 26, 2015. REUTERS/Scott Morgan

In her most contrite comments yet about an issue that has plagued her White House bid, Clinton said she had made a mistake by not using a government email account. But she maintained she had done nothing wrong and did not apologize explicitly for using a private email account for her work as America’s top diplomat.

“At the end of the day I am sorry that this has been confusing to people and has raised a lot of questions but there are answers to all these questions,” the former first lady told MSNBC in an interview.

Clinton, front-runner to be the Democratic Party nominee in the November 2016 election, has faced steady criticism from political opponents since it emerged in March that she used her own email account on an unsecured private server in her New York home for official business. Republicans say she flouted rules on record-keeping and transparency.

“I certainly wish that I had made a different choice and I know why the American people have questions about it,” said Clinton, who was secretary of state from 2009 to 2013. “I take responsibility. I should have had two accounts, one for personal and one for work-related.”

Doubts over Clinton’s trustworthiness have damaged her numbers in opinion polls, allowing liberal Vermont Senator Bernie Sanders to narrow the gap with her before the first contests early next year to pick the Democratic Party nominee for the election.

Clinton’s slump in polls has also given space for a possible run by Vice President Joe Biden. Biden’s elder son, Beau Biden, died of brain cancer in May aged 46 and the vice president said on Thursday he is trying to determine whether he has the emotional energy for a White House bid.

Clinton said she used the personal email account for convenience and did not give the issue much thought when she started her job as secretary of state.

“I was not thinking a lot when I got in. There was so much work to be done. We had so many problems around the world. I didn’t really stop and think what kind of email system will there be,” she said.

Clinton said that while she should have acted differently, she had done nothing wrong. “It was allowed and it was fully above board. The people in the government knew that I was using a personal account,” she said.

The FBI is now investigating the security of the private server and any classified information on it.

Reviews by Reuters of Clinton emails released to the public under a judge’s orders found 87 email threads that the State Department has marked to show they include information shared in confidence by foreign government officials, from prime ministers to spy chiefs.

U.S. government regulations say this sort of information, whether written or spoken, must be classified from the start and handled through secure, government-controlled channels.

The Republican National Committee said Clinton was only sorry about being the center of so much controversy over her emails.

“What’s clear is Hillary Clinton regrets that she got caught and is paying a political price, not the fact her secret email server put our national security at risk,” RNC spokesman Michael Short said in a statement.