Hillary Clinton and her high-powered campaign stand-ins are talking about trust everywhere they speak these days, and for good reason.

On Sunday's news shows, Sen. Sherrod Brown, R-Ohio, and Labor Secretary Tom Perez explicitly talked about Clinton and trust. And the candidate herself acknowledged that she has "work to do" to earn the trust of voters in her likely general election matchup against Republican Donald Trump, who suffers from a public trust deficit of a different sort, stemming from political inexperience and an impulsive style.

This week, President Barack Obama will personalize the "I trust Hillary" theme during his first appearance with his former secretary of state in battleground North Carolina. And Vice President Joe Biden will reinforce the message Friday in his hometown of Scranton, Pennsylvania, with Clinton at his side.

It's all evidence of a remarkable vulnerability that persists both despite and because of Clinton's decades of public life. But the timing of the trust campaign is no accident.

Husband Bill Clinton, the former president, met last Monday with the FBI's boss, Attorney General Loretta Lynch, on the tarmac in Phoenix in a session both say was innocent but regrettable. The FBI interviewed Clinton for more than three hours on Saturday about whether she exposed government secrets by blending personal and official business on a home email server. Clinton immediately taped a television interview in which she denied wrongdoing and repeated an acknowledgment she had slipped into a speech last week on the same day Sen. Elizabeth Warren vouched for her.

Clinton said she will do "everything I can to earn the trust of the voters of our country," remarks aired Sunday on NBC's "Meet the Press." ''I know that's something that I'm going to keep working on, and I think that's, you know, a clear priority for me."

After Warren had endorsed her, Clinton acknowledged she'd "made mistakes. I don't know anyone who hasn't."

And she defended her sometimes too-cautious style.

"The reason I sometimes sound careful with my words is not that I'm hiding something. It's just that I'm careful with my words," she said at the Rainbow PUSH Coalition's event in Chicago.

Questions about Hillary Clinton's ethics have dogged her from her days as first lady of Arkansas and later the United States during Bill Clinton's governorship and presidency, through her service a senator from New York, her failed 2008 presidential campaign and as Obama's secretary of state. So pervasive has the image been that her opponents have only to utter buzzwords like "Whitewater" — the name of the Clintons' failed land deal in which neither was implicated in wrongdoing — to invoke the image of what Trump terms, "Crooked Hillary."

Not helping make the case for trust: the Bill Clinton-Loretta Lynch meeting. "I learned about it in the news," Hillary Clinton said in the NBC interview taped hours after the FBI session Saturday. "They did not discuss the Department of Justice's review."

Was the visit inappropriate, she was asked?

"Well, I think, you know, hindsight is 20/20."

Clinton's supporters leapt in with defenses of her overall character.

"I trust Hillary Clinton in part because for a whole lot of reasons," Brown, a potential vice presidential pick, said on ABC's "This Week. "I know how she started her career advocating for the Children's Defense Fund. She didn't go off to Manhattan or to Washington to make a lot of money."

Perez repeated Clinton's own reasoning that in the quarter century since her husband was first elected president, some accusations against her have stuck, rightly or wrongly.

"The Hillary Clinton that I've gotten to know well and the Hillary Clinton that the voters of New York got to kick the tires on very well, they have always said and consistently said that we trust her," Perez, another vice presidential possibility, said Sunday on NBC's "Meet the Press." He urged voters to look at the public service work Clinton has done during her career. "That really gives me, and I think the American people, a window into her moral compass. And her moral compass is about helping those who are in the shadows."

Added Rep. Xavier Becerra, D-Calif., a third potential vice presidential pick: "The secretary has made it very clear she understands she's got to earn people's trust. She's going to work very, very hard to do that. And I give her credit for saying she's made some mistakes," he said on "Fox News Sunday." ''She's going to try to show the American people that she's going to work hard, especially for working families in America to earn their trust."