WASHINGTON — Senator Amy Klobuchar keeps having to tell Democratic voters the things they can’t have: Medicare for all, free college, mandatory gun confiscation and decriminalizing all border crossings.

In the first two Democratic debates, Ms. Klobuchar, a Minnesota moderate, refused both to embrace the party’s more liberal ideas or to draw an explicit contrast with Senators Elizabeth Warren and Bernie Sanders. Instead, she served as something of a palate cleanser between others onstage vying for the viral moment denied to her so far.

“I had to give the mom answer,” Ms. Klobuchar said Tuesday.

It’s a strategy betting on the long-term patience of Democratic primary voters she hopes will eventually pick a candidate selling herself as uniquely able to win back Midwestern voters who fled to President Trump in 2016 — if only she can attract their attention.

“I hope that these moderators will ask one of the other candidates, bring up one of my ideas and say, ‘Why isn’t this a good idea?’ That would be a nice framing,” Ms. Klobuchar said. “A lot of questions have been 30-second responses to other people’s ideas.”