Hillary Clinton answers questions from the audience following a speech in the gymnasium of Moulton Elementary School in Des Moines, Iowa, Tuesday, Sept. 22, 2015. Reuters

Hillary Clinton is in the healthiest position to take her party's nomination if the choice were made today. But she probably would lose in a general election, whereas her Democratic rivals would win, according to a Quinnipiac University poll released Thursday.

In head-to-head matchups with top Republican candidates, the former secretary of state bests only the current front-runner, real estate magnate Donald Trump. She loses to retired neurosurgeon Ben Carson (49-41 percent), to former Florida Gov. Jeb Bush (44-42) and to former Hewlett-Packard CEO Carly Fiorina (44-43). She's above water against Trump by just two points (45-43). Put another way, the margin of error basically makes the race a toss-up for matchups with Bush, Fiorina and Trump. Carson would almost certainly become president.

Hillary Clinton Presidential Candidate Profile | InsideGov

But that isn't the case for Clinton's closest Democratic competitors, who may have better chances than the national polls indicate.

In the survey of Democratic voters, Clinton tops the primary pack with 43 percent of the vote, followed by U.S. Sen. Bernie Sanders of Vermont with 25 percent and Vice President Joe Biden (who has not yet decided whether to run or not) with 18. Not all primary voters are equal, though. Since primaries don't all take place on the same day, early states can shape the race and boost momentum. A win in the first two nominating states, New Hampshire and Iowa (Sanders currently leads in New Hampshire), could propel an otherwise slightly discounted candidate (like, say, Sanders) to a more legitimate space in the race. A primary voter in South Dakota or New Mexico -- two states with late nominating dates -- could have very little to no effect on the outcome, but they might be quizzed in a national poll right now.

When Sanders is run head to head against top Republicans, he comes out on top over two of them (against Carson, 49-39, and Trump, 47-42), ties in one (Bush, 44-44), and loses in one (Fiorina, 43-44). Biden does better, beating out Fiorina (46-43), Bush (46-41), and Trump (51-40) and tying with Carson (45-45).

The survey, conducted Sept. 17-21, contacted 1,574 registered voters through live interviewers on land lines and cell phones across the nation. The poll has a national margin of error of 2.5 percent. There were 737 Republicans interviewed, with a margin of error of 3.6 percent. There were 587 Democrats interviewed, with a margin of error of 4 percent.