BOW, N.H. — As Senator Elizabeth Warren neared the conclusion of her remarks on Saturday to a few hundred activists at a house party in this small town just south of the state capital, she made a solemn vow to “protect our democracy.”

It was Ms. Warren’s first trip to New Hampshire since Robert S. Mueller III, the special counsel, testified before Congress last week about Russian interference in the 2016 election, and she told the crowd that she would “start with dreaming big.” But what she had in mind was “a constitutional amendment to protect the right of every American citizen to vote and get that vote counted” — not impeaching President Trump.

That topic didn’t come up.

Support among Democratic voters for opening an impeachment inquiry is growing, and at least 100 members of Congress are now in favor. But even in the aftermath of Mr. Mueller’s nationally televised testimony, voters bring up impeachment far less than they do policy issues, and few of the 2020 hopefuls make it central, or mention it at all, in their appeals.

Interviews with Democratic primary voters in New Hampshire and Wisconsin, and at the N.A.A.C.P. and Urban League conferences this week, yielded an unwavering belief that Mr. Trump is a lawless demagogue who must be turned out of office — but also a sense that efforts to impeach him will inevitably run aground in the Republican-controlled Senate.