The House minority leader, Nancy Pelosi, has called on the FBI director to publicly dispute Donald Trump’s explosive and so far baseless claim that Barack Obama wiretapped phones in Trump Tower during the 2016 presidential election.

Pelosi, who is a member of the House intelligence committee, said the claim “couldn’t possibly be true” and wondered whether Trump fully understood the Foreign Intelligence Surveillance Act (Fisa), which is the law that allows the surveillance of foreign powers and their agents with the approval of a secret court.

“Theoretically, do I think that a director of the FBI who knows for a fact that something is a mythology but is misleading to the American people … should set the record straight? Yes, I do think he should say that, publicly,” Pelosi said during a breakfast sponsored by the Christian Science Monitor on Friday morning.

She continued: “The character of the person – President Obama would not do that. We do not use Fisa against the American people.”

Over the weekend, Trump fired off a series of evidence-free tweets that accused his predecessor of wiretapping his phones. He called Obama a “bad (or sick) guy” and likened the alleged spying to “Nixon/Watergate”.

The FBI director, James Comey, has not commented on the matter publicly. In private, however, it was reported that Comey had urged the justice department to refute Trump’s wiretapping claims.

During the breakfast, Pelosi trod carefully around questions about the alleged connections between Trump’s associates and the Russians, reminding reporters that she could not disclose information from classified briefings. She suggested that “maybe in a short period of time” more information would become available publicly.

Pelosi did not rule out that his businesses may have been targeted as part of the FBI investigation of Russian efforts to skew the US presidential election in Trump’s favor, as several news reports have suggested.

“But we really don’t know,” she said. “I can’t know in a way that I can say here.”

The California Democrat has called for a bipartisan, independent commission to investigate reports of Russian interference in the election. She reiterated that call on Friday.

On Friday, Pelosi, who is rallying her minority caucus and the American public in an effort to save the Affordable Care Act (ACA), also known as Obamacare, which she helped pass with President Barack Obama in 2010, mocked the president’s attempt to win over conservatives to the Republican repeal legislation.

“I find the charm offensive, offensive. I think he’s making fools of his own people, quite frankly,” Pelosi said. “You don’t agree philosophically with what the legislation is? Let’s go bowling in the White House.”

The president invited members of the House Freedom Caucus, who are ideologically opposed to parts of the American Health Care Act, the ACA replacement plan, to bowl at the White House in an effort to win their support for the legislation. If the House members revolt, they could derail the bill.

Despite broad opposition to the plan from influential conservative groups as well as medical groups, the White House is confident Republicans will succeed in shepherding the plan through Congress.

“This bill will land on the president’s desk. He will sign it,” the White House press secretary, Sean Spicer, said on Thursday. “We will repeal Obamacare.”

Pelosi emphasized that she did not know whether the repeal legislation would be successful or not, but said public sentiment on Obamacare was in Democrats’ favor.

“When we talk about the taxes – you know where a lot of those wealthy people live who are going to get those tax breaks? They live in blue states,” she said. “You know where a lot of those poor people are who are going to lose their care? They live in red states and a lot of them voted for Trump. They didn’t vote, though, to have their healthcare taken away.”

