"By the time we get to 2020, Donald Trump may not even be president", she continued. In her speech, Warren pledged not to accept any lobbying or super PAC money, challenging other Democrats running in the primary to do the same. She said the party should ask: "Are we going to let him use those to divide us?"
Warren said she believes the country is facing "dangerous moment", according to CNN.
During her first of three events Sunday in eastern Iowa, Warren said the president shouldn't be allowed to dictate the direction of the campaign with divisive attacks.
Trump has frequently taken digs at Warren by calling her Pocahontas, a reference to the native woman who lived in present-day Virginia in the 1600s and agreed to marry an English colonist to help ensure peace and protect her people.
Warren has made a decision to ignore what she called Trump's "every day efforts to divide and distract", a campaign spokesperson told CNN.
AIPAC doesn't contribute directly to candidates. Which pro-Israel groups do?
Omar responded to one critic who asked the MI congresswoman who she believes is paying American politicians to support Israel. Leading Democrats have publicly rebuked one of their own Muslim congresswoman after she sparked accusations of anti-Semitism.
Warren herself may "not be a free person" soon.
As well as special counsel Robert Mueller's ongoing investigation into Russian meddling in the 2016 election, President Trump faces a probe by the House intelligence committee of his inaugural committee over illegal foreign donations, as well as inquiries into practices at the Trump Organization.
"These are serious investigations", she told reporters.
The more traction Warren's campaign gains, though, the more it undermines her claim that "the rich and powerful have rigged our political system", writes Ira Stoll.
With last month's indictment of Roger Stone, Trump's longtime friend and adviser, 34 people have been charged in the Mueller investigation, and six Trump associates have pleaded guilty. She's apologised for claiming Native American identity on multiple occasions early in her career.
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.
It was at least the third time in a week that Warren has apologised for her past self-identification.