It was a straight up question that Sen. Dianne Feinstein admitted she wasn’t expecting when she came to The Chronicle Tuesday to pitch her new California water plan.

As someone who worked with Hillary Clinton for nearly a decade in the Senate, what in your view was her signature accomplishment as a senator?

Feinstein, who arrived at the meeting with five aides toting thick briefing books outlining her new water policy proposal, paused for a few seconds to ponder the career of Clinton, whom she has endorsed.

“Golly, I forget what bills she’s been part of or authored. I didn’t really come prepared to discuss this,” Feinstein said during a wide-ranging discussion with The Chronicle’s editorial board, and several news reporters and editors. “But she’s been a good senator. There are things outside of bills that you can do, and I know that she’s done them for her state.”

Feinstein said Clinton, who was elected to the Senate from New York in 2000 and left when she was appointed secretary of state by President Obama in 2009, played a powerful role in helping New York City secure $20 billion to rebuild after the Sept. 11 terrorist attacks. Prompted by an aide, Feinstein explained how Clinton helped the Child Health Insurance Program, which helps millions of low-income kids, get off the ground when she was first lady in the 1990s.

“I should have a list,” the famously well-prepared Feinstein said. Turning to an aide, she said with a smile, “Get on Google.”

Part of the challenge, Feinstein said, is that because the Senate is dominated by those with more seniority, it is tough to push through your own legislation. Feinstein said she wouldn’t have had the juice to do things like press for a five-year investigation of the CIA’s interrogation techniques unless she was a senior member of the Intelligence Committee.

“I couldn’t have done that as a freshman (senator) or even as a sophomore,” Feinstein said. “She was never there long enough to achieve the degree of seniority that affords her the ability to do more.”

That said, Feinstein was being a bit modest. She was only in Washington a couple of years when she fought the National Rifle Association to spearhead an assault weapons ban in 1994 and was an architect of the 1994 California Desert Protection Act, which made Joshua Tree and Death Valley into national parks.

Feinstein was a bit more effusive about Clinton’s signature accomplishments as secretary of state, saying she was instrumental “in pushing through” the New START nuclear arms treaty with Russia in 2011. “That was Hillary,” she said.

Feinstein also praised Clinton’s readiness for the job, saying she “has been able to know and understand world leaders on an unprecedented basis. She will know more of the leadership of the world than anyone who has ever been elected to the presidency. She will know whom to go — and that is important.”

“I do believe she is a role model for women in this area,” she said. “And the opportunity to have the first woman president — it may never be there again, I don’t know, but it’s there now. I think of all the nominees, she is the most skilled.”

Despite her endorsement, Feinstein is not one of those Democrats who thinks Sen. Bernie Sanders should exit the race, even though the Vermont senator trails Clinton in the delegate count.

“He believes that he has an ability to overtake Hillary. We’ll see,” Feinstein said. “He’s a realist. I don’t think he’ll want Donald Trump to be elected president. He (Sanders) is a good man,” Feinstein said.

The Clinton camp seems to be running a bit scared of Sanders these days, thus far declining his offer to debate in New York before that state’s April 19 primary, namely because he’s running too “negative” of a campaign. (Even though Sanders never rails on Clinton’s email scandal or mentions the word “Benghazi” as a more “negative” opponent might.)

On Monday, Clinton pollster Joel Benenson told CNN Monday that “Sen. Sanders doesn’t get to decide when we debate, particularly when he’s running a negative campaign. Let’s see if he goes back to the kind of tone he said he was going to set early on. If he does that, then we’ll talk about debates.”

Feinstein doesn’t think Sanders has been negative.

“He isn’t slash and burn. He’s talked about his issues and I think been constructive and I think there’s a high likelihood he’s not going to change from that,” Feinstein said.

Joe Garofoli is the San Francisco Chronicle’s senior political writer. Email: jgarofoli@sfchronicle.com Twitter: @joegarofoli