Sen. Rand Paul (R-KY) is the only 2016 presidential candidate in either party who participated in a New York Times survey regarding scaling-back presidential power.

“This is one of the defining issues of 2016, changing the trajectory of the balance of power. Power in the wrong hands is a dangerous thing, I am the only one pledging to return power to the states and above all else will protect and defend the Constitution of the United States,” Paul told Breitbart News.

“As the Iowa caucuses and New Hampshire primary approach, voters appear unlikely to know the answers to such questions. Both Mr. Trump and Mrs. Clinton — the leading candidates for the Republican and Democratic nominations — declined to answer questions submitted by The New York Times about their understanding of the scope and limits of the powers they would wield if elected,” Charlie Savage of the New York Times wrote on Friday.

“They are hardly alone. Of the Republican contenders, only Rand Paul responded. The campaigns of Jeb Bush, Ben Carson, Chris Christie, Ted Cruz, John Kasich and Marco Rubio, among others, declined or did not answer. Mrs. Clinton’s two Democratic rivals, Martin O’Malley and Bernie Sanders, also turned down the survey.”

The questions from Savage to the various candidates—again, which Paul is the only candidate who answered—focus on matters like prosecutorial discretion, signing statements, executive actions, treaties, executive agreements with other nations, secrecy, handling of leaks, war powers and more.

Savage, who is a Pulitzer Prize-winning reporter, used to work at the Boston Globe. In 2008, he asked candidates similar questions. At the New York Times in 2012, he received responses from most candidates.

“Virtually all the serious candidates engaged with similar surveys I submitted during the last two presidential elections,” Savage wrote. “This year’s silence suggests a striking shift in political calculus.”

“I first did the survey eight years ago while working at The Boston Globe,” Savage wrote. “Nine of the 12 campaigns I contacted decided to participate, including both eventual nominees — Mr. Obama and John McCain.”

In December 2007, now President Barack Obama—then a Senator who hadn’t yet beaten now former Secretary of State Hillary Clinton in the primaries—wrote back to Savage. “The American people need to know where we stand on these issues before they entrust us with this responsibility,” Obama said then.

“In 2011, working for The New York Times, I updated the survey to address new controversies and submitted it to the Republican primary field,” Savage continued. “Five of the seven campaigns I contacted participated, including the eventual nominee, Mitt Romney, who said he agreed that all would-be presidents should tell voters their answers to such questions.”

He then quotes Romney as saying about these questions and issues: “They deserve serious consideration by all candidates.”

But it looks like only Paul is taking these issues and questions seriously in 2016.