“The more lights we turn on, the more Republicans and their cronies will scatter. And the more they try and hide, the harder we’ll work to uncover the truth. … Help us keep the pressure on ­— give $25 or more to help us hold Republicans accountable,” the email says.

The strategy highlighted an emerging difference between Republican and Democratic outside groups: While Republicans have had a much easier time raising money and have outspent Democrats many times over on advertising, several major Democratic groups have fashioned themselves into largely opposition-research organizations, records suggest.

The tactic, they hope, will allow them to overcome a fundraising disparity by coming up with particularly compelling nuggets of information that go viral, rather than saturating the airwaves with traditional talking points, as their Republican counterparts, including Crossroads GPS, have done.