FITCHBURG - Avoiding even scant mention of a possible presidential run in 2020, U.S. Sen. Elizabeth Warren said at a town hall meeting Thursday night her sights are firmly set on her re-election bid.

Crowds lined up around the Conlon Fine Arts Center at Fitchburg State University Thursday night to hear the Democratic incumbent speak and answer audience questions. She will face one of three Republicans in the November election: Geoffrey D. Diehl, John Kingston or Beth Lindstrom. (This paragraph has been corrected. There are three Republicans seeking the seat.)

Ms. Warren Thursday night wove personal stories with policy statements and critiques. She said she remains optimistic about American government while at the same time admitting she is deeply worried about the direction the country is headed.

“This is a frightening moment in America but it’s also an exciting moment in America,” she said, adding that it’s time for people to “come off the sidelines” and get politically active.

She railed against what she described as the corrupting influence of money in everything from health care to gun control legislation. Asked about making schools safer from gun violence, she said the National Rifle Association has blocked sensible, popular gun control legislation at every turn.

“Why can’t we do it? Because the NRA holds the federal government by the throat,” Ms. Warren said.

She said elections matter, and have shaped policy in this country in a way that has slowly stripped away protections and benefits from the middle class and pushed wealth upward.

Ms. Warren juxtaposed tax bills she said gave away trillions of dollars in breaks to corporations and the wealthy to a student loan crisis she said is creating a “snowball” of debt that stifles the economy.

“Student loan debt, to me, now signifies an America that has gotten way off track,” she said.

Asked how young people not old enough to vote can get involved, Ms. Warren said they can volunteer, but also urged them to talk to people who don’t agree with them politically. She said they should reach out and find one topic important to them, and show how it’s personal to them.

Asked whether her comment last week that the criminal justice system was racist “front to back” was too much of a blanket statement, Ms. Warren said she wasn’t speaking about an individual, but was looking at systemic factors that, for example, result in arrests and prosecutions for crimes like marijuana possession that disproportionately impact African-Americans.

She said blacks and whites smoke pot at roughly the same rate, but said an African-American is 3.5 times more likely to be arrested for marijuana possession.

She said she has worked on bills that address some of those disparities, including one that would back off federal enforcement when states legalize marijuana.

Telling her own personal story about how her mother’s minimum-wage job helped her family stay afloat financially, Ms. Warren said her story wasn’t just about her mother - it was about a time when the government truly worked for the people.

She said when her mother went to get that job after her father suffered a heart attack, she was able to support her family because the minimum wage was designed to give people a pathway to the middle class.

Ms. Warren said today, a full-time minimum wage wouldn’t pay the rent and wouldn’t help keep a mother and baby out of poverty.

“There was a time when government looked at the minimum wage and said, ‘What does it take for a family to survive?’ ” Ms. Warren said. “Today, I sit at those hearings, and I listen to what government decides, and that is ‘what does it take to maximize the profits for Walmart and McDonald’s?’ ”

Ms. Warren said “there are more of us than there are of them,” but said there are reasons why government has stopped working for the people. She said money has corrupted government, and has been combined with issues like gerrymandering and interference from foreign governments in U.S. elections.