It was a brief, shining moment for congressional Democrats: As details of Trump’s Ukrainian phone call spilled out, and as House Democrats revved the impeachment engine, early polls evidenced strong support for removing Donald Trump from office. Though much of that support came from Democrats, critically, it also came from Independents: A late October Gallup poll put Independents in favor of removing Trump from office at 53% to 44%, and a Morning Consult poll in early November revealed an even greater gap, 49% to 34%, in favor of removal.

That early enthusiasm represented a potential bonanza for the Democrats, albeit a surprising one. Independents tend to be moderate and pay less attention to newsbreaks and politics, and are an unlikely group to suddenly surge in support of a precipitous step like impeachment. Independents are also one of the keys, if not the key, to the 2020 elections. According to Gallup, self-identified Independents make up roughly 40% of the electorate. Many of these voters are closet partisans, reliably voting for one party or another, but enough of them—call it somewhere between 10% or 20%—are true “persuadables” or “movables” whose votes are up for grabs. Even a modest shift in allegiance among this group could determine the outcome next November.