Addressing the California Democratic Party's annual convention, Pelosi cited former special counsel Robert Mueller's report into alleged Russian interference in the 2016 presidential election.
“In his report, special counsel Mueller warned us in the starkest terms that there was an attack on our election and an attack on our democracy," Pelosi said. "Why won't the president defend us from this attack? What is the president covering up? We must investigate the president's welcoming of the assault on our democracy,” she added.
"We will go where the facts lead us. We will insist on the truth. We will build an ironclad case to act," Pelosi said.
Pelosi and House Democratic leadership have played down talk of impeachment, even as a growing portion of the House Democratic Caucus calls for an inquiry. Pelosi told late-night host Jimmy Kimmel on Thursday that the party had to be prepared to build a case.
Impeachment discussions have been initiated by House Democrats. House Judiciary Committee Chairman Jerrold Nadler, who would chair impeachment hearings, said Friday there is justification to begin impeachment proceedings against President Trump, but added that public support must be behind the move before hearings begin.
Fifty House Democrats have called for opening an impeachment inquiry so far. Rep. Justin Amash remains the only Republican who also has called for impeachment.