A big part of Hillary Clinton's perceived appeal as a presidential candidate in 2016 is this: No one -- or, at least very few people outside the ranks of the most conservative Americans -- doubts that she could do the job. Her resume is stuffed with just the sort of jobs -- senator, secretary of state, etc. -- that most people see as a proving ground to be president. Her argument in the campaign to come is almost certain to highlight that background, that she will be ready to go on day one in office.

That's why a new piece of polling data from the NBC-Wall Street Journal survey released  this week should worry Clinton and her team. Here it is:

Yes, it's notable that fewer than four in 10 registered voters prize "a more experienced and tested person even if he or she brings fewer changes to the current policies." But to my mind, it's even more interesting that the desire for "a person who will bring greater changes to the current policies" even if that person has less experience is higher now than even in the summer of 2008 -- when Barack Obama was sweeping to the presidency on a message of change.

That's bad news if:

(a) You have been in the national political spotlight continuously since (at least) 1992.

(b) You are widely regarded as the establishment of the establishment within the Democratic Party.

(c) You played a major role in the current administration.

(d) You are running to keep the same party in power for three consecutive presidential terms.

That, my friends, describes Hillary Clinton to a T. But wait, there's more. Clinton, who will be 69 on election day, will be the older of the two general election nominees -- no matter who Republicans nominate. (Jeb Bush, at 61, is of Clinton's generation. People such as Marco Rubio and Ted Cruz, both in their early- to mid-40s, are significantly younger.) Now age is, of course, not the sole way in which "change" or "experience" is litigated in the context of a presidential campaign (or in life). But it can -- and does -- matter in the broader perception game. Case in point: the 2008 presidential race. The fact that Obama was 25 years John McCain's junior made it far easier for the Illinois senator to make the case that he represented change while McCain was the status quo.

Clinton's biggest challenge in the 2016 race is -- and always will be -- to package herself and her ideas as new and fresh. The data above suggest that voters are putting even more of a premium on the need for change -- further raising the stakes for Clinton to reimagine her years in public life.

Former secretary of state Hillary Clinton told reporters at the U.N. that she chose to use a personal e-mail account because she thought it would be easier to use one device rather than two. (UN Web TV)