Generation Citizen hopes to raise $1 million in 2016 to finance its efforts. The group has already received $230,000, Mr. Warren said, adding that none of the money came from politicians or partisan organizations.

But some leading Democrats, most notably Representative Nancy Pelosi of California, the House Democratic leader, have supported such changes, spurring partisan suspicions about the effort. In a speech this year before a meeting aimed at bringing young leaders and progressive organizations together, Ms. Pelosi said she was “all for” lowering the voting age to 16 or 17 “because when kids are in school, they’re so interested, they’re so engaged.”

Mark Tapson, the editor in chief of Truth Revolt, a conservative website, said that Ms. Pelosi was trying to “rope in young voters” who may be more inclined to vote with popular culture idols, who tend to be liberal.

“When they see, for example, that Barack Obama slow jams with Jimmy Fallon or hangs with Jay Z and Beyoncé,” Mr. Tapson said, “many 16-year-olds feel a connection with him not because of his policies necessarily but because that makes him cool.”

But others see teenagers as less politically predictable.

“I actually could see a lot of them flocking around Donald Trump because they could identify with his immaturity,” said John J. Pitney Jr., a professor of politics at Claremont McKenna College in California and the former acting director of the Republican National Committee’s research department. “Conversely, they might not be too crazy about Hillary Clinton because she might remind them of their mother. Who knows?”

Daniel Hart, a psychology professor at Rutgers University who has studied whether the voting age should be lowered, played down concerns about the impulsive tendencies of teenagers.

“There is a tendency to overestimate how thoughtful and how informed the decisions of other voters are,” Mr. Hart said, referring to people older than 18. “It isn’t the case that, particularly in municipal elections, a lot of voters are spending an enormous amount of time learning before making these sorts of decisions.”