If you really want to understand underlying voter sentiments in any Presidential election season, polling is a quick and easy way to get that snapshot. However, there is a fair amount of subjectivity inherent in any poll, and variables like the person/firm conducting the polling, the timing of the poll, and similar considerations can affect the poll results. Another way of gauging voter sentiment is to analyze underlying changes in partisan voter registration, since new registrants tend to register with the party who at that point in time had that voter’s support.

Of the many signals (a bad economy, $4 a gallon gas, a competitive Democratic contest) that pointed to a Democratic year in 2008, the Democrats also had a very good year in terms of Democratic voter registration. What happened to that “Democratic surge” since President Obama was inaugurated?

To answer that question, we analyzed partisan voter registration in several competitive states between 2007 and July 2012. Here’s what we found (keep in mind that not all states register voters by party):

Florida

Ever since the 2000 Presidential election contest (and the aftermath) between George W Bush and Al Gore, Florida has become a closely watched state every election cycle, and this year will be no exception. In 2007-2008, Florida was one of several states that were at the epicenter of the home foreclosure crisis, and Democrats (who did not control the Presidency then) naturally reaped a huge benefit from this. During 2008, Democrats (who have always had a plurality of registered voters in Florida) saw their voter registration advantage double, from 304 to 692K. Since President Obama carried the state by 236K, it’s fairly obvious that he benefitted from this Democratic voter registration surge.

Since then, Democrats have seen their fortunes change: their voter registration advantage has declined from 692 to 439K (curiously, this 253K decline in Democratic voter registration advantage is about the amount by which President Obama carried Florida in 2008). In absolute terms, this means that Democrats have lost 5% of their registered voters. Republicans since January 2009 have added 24K to the voter rolls, and Independents have added 208K. Furthermore, in the first half of 2012, Republicans have out registered Democrats 35 to 24K, although Independents have seen an 85K increase in their numbers.

The 30 day average of recent polls in Florida shows President Obama with only a 46-45% advantage over Mitt Romney. When you combine that with Republican gains in 2010 at the legislative, statewide and Congressional level, Mitt Romney is currently in a good position to carry the state in November.

Colorado

Even though Colorado has more often than not voted Republican in Presidential contests, George W. Bush never received more than 52% of the vote here in either of his two contests, and Barack Obama received 54% of the vote here in 2008 – the biggest winning margin for any Presidential candidate here since 1988.

There were signals that Colorado was moving towards the “tipping point”, however, if you look at voter registration trends. In 2008, Democrats erased the 130K voter registration advantage Republicans had in January of that year. This alone matters when you consider that in 2004, George W. Bush only carried the state by 100K votes.

Since then, Republicans have regained their voter registration plurality, although even more voters have registered as Independents: 63% of the increase in registered voters since January 2009 has accrued to the Independents. Among remaining voters, Republicans have registered twice as many voters as the Democrats have. If you were only to consider new registrations in 2012, however, 48% of new voters have been Republicans, while 31% have been Democrats.

The 30 day average of recent polls in Colorado shows President Obama with a 46-44% advantage over Mitt Romney. While we think Mitt Romney is on stronger footing than John McCain was in 2008, this will be a competitive state for two reasons: (1) Republicans did not do as well here in 2010 as they did in Florida – while they picked up two House seats and a handful of legislative seats, Democrats won the Senate and Governor’s races on the ballot that year, and (2) the spike in Independent voter registrations between 2009 and 2011 complicates the picture in terms of voter attitudes, unless you believe that Colorado’s independents have soured on President Obama like independents have nationally.

Iowa

Stereotypically, people think that Iowa is filled with corn fields and rural Midwestern Republican voters, but the state also has significant blocs of unionized voters, and in fact, Republicans have only carried the state once (which was in 2004) in Presidential elections since 1984. And even then, the Republican victory margin was only 10K votes.

In fact, Iowa exhibited similar behavior as Colorado did in 2004 and 2008: narrow wins for George W Bush in his 2004 re-election campaign, and a 54% victory by Barack Obama in 2008.

There were warning signs for Republicans that Iowa was moving Democratic in 2008 if you looked at voter registration: that year, new Democratic registrations exceeded Republican registrations by a 5 to 1 margin. To put this in perspective, a Democratic voter registration plurality of 33K in January 2008 increased 252% to 116K in January 2009. When you consider that former President Bush only carried the state by 10K voters in 2004, this 83K Democratic spike in 2008 helped President Obama carry the state – his margin of victory was 147K voters.

This Democratic voter registration edge has nearly vanished since then – they only have a 5K voter registration edge as of July. In fact, Democrats have (just like in Florida) suffered an absolute decline in their numbers. Since President Obama’s inauguration, the number of registered Democrats has declined 10%, or 71K. Curiously, the number of Independents has declined as well: there are 31K (4%) less Independents than there were in January 2009. Republicans have fared better: their registration numbers have increased 40K, or 6%. The numbers are even more troubling for Democrats if you consider 2012 voter registration trends: in the first seven months, Democrats have lost 9K (and Independents 18K), while Republicans have increased their numbers by 25K – over half their total increase since January 2009 has occurred in 2012 alone.

The 30 day average of recent polls in Iowa shows President Obama with a 48-43% advantage over Mitt Romney. However, Republicans made legislative gains in 2010 and defeated a Democratic incumbent Governor that year. This, combined with strong Republican voter registration, means that Iowans are in a more Republican mood than they’ve been for years. It also doesn’t hurt that the GOP had a competitive Presidential primary, while President Obama didn’t. However, it’s also worth noting that 36% of Iowa’s voters are Independents. Since Independents have been President Obama’s “Achilles Heel”, he has to shore up support among this voter bloc of he wants to carry Iowa again.