The Strib has a poll out this morning showing Dem Al Franken leading Repub incumbent Norm Coleman by 9 percentage points with Indy Partyite Dean Barkley at a strong 18.
The result stands in sharp contest to the most recent public poll by Survey USA for KSTP-TV, which showed Coleman up by 10 points.
The SUSA poll was taken Tuesday-Wednesday; the Strib’s Tuesday-Thursday. SUSA sampled 725 likely voters, compared with the Strib’s 1,084 likely voters. Both polls have a margin of sampling error of plus/minus 3.7 percentage points.
We’re grown-ups here and used to polls that disagree, but this level of disagreement is beyond normal.
Coleman campaign spokester Luke Friedrich questioned the Strib’s methodology. Republican partisans are already teeing up the “Red Star” epithet in the poll story’s comments.
If you want to know which poll to believe more, the Strib’s has the larger sample size and the advantage of the older, more established human interview methodology. SUSA uses robotic voice interviews.
One more suspicious indicator about the SUSA/KSTP poll is that the same poll of the same sample found John McCain with a slight lead over Barack Obama in Minnesota, which is contrary to the findings of most recent Minnesota prez polls.
Digging a bit deeper into the results, here are two other key differences:
Party identification. Simply put, the Strib survey has more self-identified Democrats (and Independents) and fewer Republicans. The Strib’s D-R-I breakdown is 42-26-27 — a 16-point gap favoring the D’s. For SUSA, it’s 37-30-21 — only a 7-point DFL tilt.
The Barkley breakaway. The Strib poll says the Independence Party nominee takes equally from partisan bases: 12 percent of Republicans and Democrats. But SUSA says Barkley nabs almost twice as many Dems (19 percent) and Repubs (10 percent).
The Strib may be on to something if the Democratic Party is picking up adherents in these panicked bailout times, and if Republican partisans are as enamored of Barkley as disaffected DFLers.
On the other hand, if you believe the partisan index is near recent norms and Barkley is likelier to peel off Democrats, SUSA seems to confirm your hunch.
The Strib’s finding of a big Franken leadis simply unexpected because no other poll has shown anything like it. Here is a list of recent polls in the race, up to but not including the Strib’s.
It seems likely that the true state of the race is somewhere between the two polls, but there’s a lot of room there, and we’ll never know.
The next poll will be taken after the first three-way debate in the race, Sunday evening in Rochester. So far as we know, there will be no statewide TV broadcast (why not?) but Minnesota Public Radio will air the debate Sunday evening, 7 p.m.