Geraldine A. Ferraro, who in the waning days of her vice-presidential bid increasingly refers to an army of silent voters planning to vote Democratic, predicted today that she and running mate Walter F. Mondale will benefit on Election Day from a "conscience factor."

"I'm convinced that when they get into that booth, that 30 seconds when they're all alone and when they don't have somebody telling them how they're supposed to vote, that they're going to think about their kids and the future, and they're going to think about nuclear war, and the other issues, and they're going to vote for us," Ferraro said on the Phil Donahue television show.

Appearing before a predominately female television audience estimated at 7 million, Ferraro spent much of the hour-long show defending her integrity and that of her husband, John A. Zaccaro.

"Have I, in any way, used any of my offices, as a prosecutor or a member of Congress, for my own personal benefit, or for my husband's personal benefit? No," she declared.

At one point, there was an awkward misunderstanding between Ferraro and Donahue after the talk show host referred to a Wall Street Journal report that Zaccaro had received a fee in a real-estate transaction now being scrutinized by a New York grand jury.

"Wait, wait, wait, wait, wait," Ferraro interjected. "If The Wall Street Journal had said what you just said, there'd be a libel suit out immediately. They did not, did not say my husband was a thief."

"I didn't say 'thief,' " Donahue replied. "I said he received a 'fee.' "

Ferraro, who referred to herself as "a credible candidate," said the recent flurry of news reports about her husband's business transactions and the alleged arrest of her parents in 1944 had not distracted her.

"I get up and do what I have to do," she added. "I have tremendous powers of concentration."

Later in the day, during a rally in West Frankfort, Ill., Ferraro blamed the Reagan administration for failing to act sooner in sending relief shipments to famine-wracked Ethiopia.

"They did not act when everybody saw the problem, and now the problem has become a tragedy," she said. "I want an administration that sends overseas fewer tools for war and more Food for Peace."

As she has for the last three months, Ferraro cast the election as a referendum on arms control. "There is no greater American principle than peace with other countries and that requires ending the arms race," she told 4,000 supporters in a high-school gymnasium.

According to Ferraro strategists, her schedule for the remaining week of the campaign is dictated in part by attempts to block Republican victories in Senate races.

"She wants to help wherever she can. No question it's very much on her mind . . . . She wants to help good candidates who are in tight races," campaign manager John Sasso said, specifically citing Rep. Paul Simon (D-Ill.), who is trying to unseat incumbent Sen. Charles H. Percy (R-Ill.).