The debate within the Democratic Party has occurred largely under the radar, and no potential 2016 Democratic presidential candidates have taken up the mantle in the way Paul has among Republicans, despite polling that shows a sizable constituency for just such a candidate.

A Washington Post-ABC News poll last week showed similar levels of privacy concerns in both parties, with more than six in 10 liberal and moderate Democrats saying the NSA’s surveillance programs intrude on Americans’ privacy.

Privacy concerns in the Democratic Party have waned since Obama took office, but there remains a large number of voters for a potential 2016 contender to win over. That is particularly true given that former secretary of state Hillary Rodham Clinton and Vice President Biden are closely associated with the administration’s national security programs and lead the field of likely candidates.

Julian Sanchez, a research fellow at the libertarian Cato Institute, said Wyden is doing yeoman’s work but acknowledged that he’s “not really a rabble-rouser in the mold of someone like Rand Paul.”