John McCain may help Republicans buck the historic trends that should give the Democrats the White House, according to the Wall Street Journal and NBC. Despite voters wanting to elect a Democrat by a 13-point margin, McCain sits in a virtual tie with both Barack Obama and Hillary Clinton, indicating a large amount of discontent with the specific Democratic candidates. In this case, even a tweaked sample of registered voters doesn’t help:

A couple findings in the new poll capture how conflicted Americans are. By a 13-point margin, 50% to 37%, registered voters say they would prefer a Democrat to be elected president. When asked to choose specifically between Arizona Sen. McCain and either Democrat, the results in each case are a statistical tie.

Illinois Sen. Obama edges Sen. McCain by 47% to 44%, while Sen. Clinton, of New York, beats the Republican by a near-identical 47% to 45%. The poll, which surveyed 1,012 registered voters March 7-10, has a margin of error of 3.1 percentage points.

Chief among the strengths of the Republican nominee-in-waiting is his experience with national-security issues, as a naval aviator and longtime senator. “Americans can visualize John McCain behind the desk in the Oval Office,” said Mr. Hart. “The difficulty is where his policies are, and is he going to take the country where it wants to head.”

Of 10 attributes measured in the poll, Sen. McCain scored highest for “being knowledgeable and experienced enough to handle the presidency.” Nearly two-thirds of voters agreed — up 12 points from December, when both parties’ nominating races were getting under way. His next-highest ratings, from 61%, were for strong leadership and for readiness to be commander in chief.

McCain has strong likability factors in the survey. Only a minority of Democrats dislike McCain, and he has a +20 overall, 47-27. Hillary gets a 45-43 rating for a +2, while Obama gets the best rating of a +23, 51-28.

Once again, though, the sampling for the survey has to call some of the conclusions into question. The WSJ/NBC poll included registered voters, 11% of which didn’t vote in the last presidential election. That seems to undermine the predictive value of this poll.

Also, we have a repeat of the party breakdown issue. Thanks to the strange manner in which question 11a is asked, the demographics can be read a couple of different ways, but none of them come close to reality. Rasmussen shows party identification in the US as 38.7% Democrat, 33.1% Republican, and 29.2% independent or third party. This poll has 34% Democrats, but only 25% Republicans and 37% independents. It’s not as bad as the Washington Post or CBS polls, but it will skew the results accordingly.

Given those factors, a virtual tie for McCain bodes rather well for the general election. Even with Republicans undersampled, he gets within the margin of error of Obama and Clinton.