LAWRENCE, Mass. — Senator Elizabeth Warren of Massachusetts formally announced her 2020 presidential bid Saturday, calling for “fundamental change” on behalf of working people and arguing that President Trump is “just the latest and most extreme symptom of what’s gone wrong in America.”

Speaking on a clear, chilly day against a backdrop of old red brick mill buildings at the site of one of the nation’s most famous labor strikes, she said workers now, like workers then, had had enough. She said that replacing Mr. Trump, whose administration she called “the most corrupt in living memory,” was only the first step in fighting back against a system tilted in favor of the wealthy.

“It won’t be enough to just undo the terrible acts of this administration,” Ms. Warren said. “We can’t afford to just tinker around the edges — a tax credit here, a regulation there. Our fight is for big, structural change.”

The selection of Lawrence was symbolic: In 1912, a historic labor strike was started by a group of women at Everett Mill, where Ms. Warren made her announcement. The senator drew on the strike as a story of women, many of them immigrants, taking on a stacked system and triumphing by gaining raises, overtime and other benefits.