BERRYVILLE, Va. — For more than a year, Democrats have raged against now-President Trump, projecting their opposition as the party’s central message. In so doing, they have maintained their minority status in Congress, sustained the most stunning loss in modern presidential history and left voters with little sense of what they represent.

On Monday, Democratic leaders gathered 70 miles from Washington — in a town of some 4,000, in a district represented by a Republican, in a county carried easily by Mr. Trump — to try something else.

“Too many Americans don’t know what we stand for,” Senator Chuck Schumer of New York, the Democratic leader, told a sweat-soaked crowd of about 100 at a park here off Main Street. “Not after today.”

Such is the battle cry of a party in the wilderness, straining to win support even while staring down a historically unpopular president consumed by Russia-specked scandal. Now Democrats are training their attention elsewhere, unfurling a set of proposals aimed squarely at voters who see a gap between Mr. Trump’s populist campaign message and the reality of his tenure.