A new poll provides a fresh take on a still smoldering question about the decisive Republican wins in 2009 and 2010: did voters change their minds following Democratic victories in previous elections, or did left-leaning voters simply decide to sit out the midterms?

The ultimate answer – with its major implications for upcoming elections – has eluded analysts and potential office-seekers alike. But a new, detailed breakdown of the American electorate by the Pew Research Center shines a light on significant changes in voters’ views over the past few years, but also the major consistencies.

What’s the verdict from the Pew data? A decidedly split decision, with the study suggesting that the composition of the electorate was a somewhat bigger factor than changing views among those who voted in both elections.

When it comes to voting patterns, key groups shifted toward the GOP in 2010 relative to 2008, but Democratic voters also opted out. And with one important exception, the shifts in votes across groups appear poised to tack back to Obama in his bid for re-election.

Pew identifies eight types of voters: two on the right – “staunch conservatives” and “main street Republicans;” three on the left – “new coalition Democrats,” “hard-pressed Democrats” and “solid liberals;” and three mostly independent ones – “libertarians,” “disaffecteds” and “post-moderns.”

Voters on opposite ends of the spectrum – firm conservatives on one side and hard-pressed Democrats and solid liberals on the other – hardly budged between the presidential election in 2008 and the 2010 midterms. But in the other five groups – making up fully 58 percent of the electorate – the GOP picked up an average of 13 percentage points relative to the Democrats.

The more Democratic-leaning groups were also apt to not participate in 2010. (Or not recall whom they supported, a sign they may have opted out.) For the four left-most groups, the average falloff in total two-party vote was 12 points; in the three closest to the right, it went up five.

But these differences that emerged in 2010 largely subside when Obama is squared up against an unnamed Republican opponent in a hypothetical match-up.

The double-digit drop-off in vote share that hurt Democrats in 2010 disappears when it comes to the 2012 outlook: the participation falloff is chopped in half.

That’s not to say 2012 will be a re-run of 2008.

Obama obviously will have to contend with an actual, not a “generic,” Republican opponent. And within the Pew data there’s one important voting bloc that’s continues to trend Republican: libertarians.

Making up 10 percent of the electorate in the Pew typology, 70 percent of libertarians say they’d back any Republican against Obama. Barely more than half – 53 percent – say voted for McCain in 2008. These voters have far more in common with the GOP groups when it comes to views about the role of government, which has been a major focus of debate in Obama’s first two-plus years in office.

For more on libertarians and the other seven groups, see the full report. To find out where you fit, take the quiz.

Polling manager Peyton M. Craighill contributed to this report.