This is verified by a recent Quinnipiac University Poll (Taken between February 27th and March 4th of 1,944 registered voters nationwide -- with only a 2.2 margin of error) that shows Hillary would crush the current leading Republican hopefuls:
Clinton...............45%
Christie...............37%
Clinton...............50%
Rubio...............34%
Clinton...............50%
Ryan...............38%
Here is how the Business Insider (certainly no bastion of liberal thought) puts it:
As Republicans begin to gear up for the 2016 presidential race, GOP insiders have one major concern that wasn't mentioned anywhere in the RNC's autopsy report.
Her name is Hillary Clinton, and Republicans worry that they won't have a shot against her, regardless of what changes the party makes before 2016.
Although most Republican strategists would not go on the record disparaging the party's chances, in private conversations with Business Insider, many savvy GOP insiders conceded that any Republican nominee would face an uphill battle against the former Secretary of State. "If she runs, it'll be almost impossible, I fear," one Washington-based Republican strategist told Business Insider. A New York-based GOP media strategist concurred: "It will be extremely hard for Republicans to beat Hillary in 2016," he said, adding that the difficulties would be compounded if the party nominates another candidate who fails to ignite the conservative base. . . On a national scale, Clinton left office with record-high favorability ratings — a January Washington Post/ABC News poll found that a full 67 percent of Americans viewed the outgoing Secretary of State favorably. In addition to her popularity, Clinton's national name-recognition and extensive fundraising network — not to mention her experience running a presidential campaign — make her a formidable opponent to both Democrats and Republicans. But the biggest problem for the GOP is that if Clinton decides to run, the Democratic primary will likely turn into a de facto contest to pick her running mate, giving the party a big head start in the general election. In the meantime, Republicans will likely have to slog through a contentious primary with what is shaping up to be a very crowded field.