Senator Elizabeth Warren, who has worked for months to find traction in a crowded Democratic presidential primary, stepped forward on Friday with a call to arms: President Trump must be impeached.

What followed, generally, was conspicuous silence — and not just from her colleagues in Congress.

After sidestepping the explosive issue of impeachment for months by citing the inquiry by the special counsel, Robert S. Mueller III, most of the other 17 Democratic presidential candidates have responded to the special counsel’s report with tentative remarks about impeaching Mr. Trump, demands for the unredacted Mueller findings, calls for further hearings or attempts to simply change the subject.

Anything, that is, to avoid clearly answering the question of whether lawmakers should remove the president from office.

Underpinning the candidates’ calculations are complex sets of short- and long-term incentives. Democratic hopefuls could receive a fund-raising boost by embracing impeachment and energizing liberal donors. But some strategists and lawmakers say that a failed effort would only strengthen Mr. Trump’s re-election chances, allowing him to claim further vindication.