Speaking at a campaign event on Sunday, the day after she announced her intention to run for president, Warren said that Trump may not be a "free person" by the end of the election.
"By the time we get to 2020, Donald Trump may not be president," Warren said in Cedar Rapids, Iowa, The Washington Post reported. "In fact, he may not even be a free person."
When asked to elaborate, Warren said: "Come on, how many investigations are there now? Its no longer just the Mueller investigation, theyre everywhere. And these are serious investigations."
Trump is facing an ongoing federal investigation by special counsel Robert Mueller, who is examining Russian interference in the 2016 election, and an expanded House investigation into his finances and alleged ties to Russia.
There are also investigations underway into Trump's business and charity dealings, investigators working out whether he is unjustly profiting from his presidency, and whether he violated campaign finance laws. In total, Trump faces more than a dozen investigations.
Warren said that she typically doesn't mention Trump at events because she thinks he is a symptom, not a cause, of the issues she is campaign on.
She said the Democrats will not succeed by just opposing Trump, which will not "make the changes that this country really needs."
Warren was speaking the day after Trump attacked her 2020 candidacy , calling her "Pocahontas", and seemingly making a joking reference to the Trail of Tears a genocide that forcibly displaced tens of thousands of Native Americans and caused the death of roughly 4,000 in the mid-1800s.
"Today Elizabeth Warren, sometimes referred to by me as Pocahontas, joined the race for President," Trump tweeted on Saturday. He also wrote: "See you on the campaign TRAIL, Liz!"
Read more: Trump appeared to joke about the Trail of Tears in a tweet mocking Elizabeth Warren
Trump's tweet came shortly after Warrens formal declaration, where she urged a crowd in Lawrence, Massachusetts to back the "fight of our lives" against corruption and slanted regulations in Washington.
"This is the fight of our lives," Warren said. "The fight to build an America where dreams are possible, an America that works for everyone. I am in that fight all the way. And that is why I stand here today: to declare that I am a candidate for President of the United States of America."
The US constitution does not prohibit a sitting president from being indicted while in office, and there is no law that says Trump is immune from criminal prosecution.
Legal scholars are divided on the issue, and the Supreme Court has never addressed it.
Current Department of Justice policy holds that a sitting president cannot be indicted, which is a major barrier to any action being taken.
A former Justice Department legal expert wrote in The New York Times in December saying that Trump technically could be indicted, but that it was unlikely to happen.
