Rasmussen Reports data shows that public perceptions of both Barack Obama and John McCain are shifting rapidly during Election 2008. That same data suggests perceptions will continue to change through Election Day ( see video).

In December, before the Iowa caucuses launched Obama’s successful campaign for the nomination, the Illinois Senator was seen as politically liberal by 47% of voters nationwide. By April, that number had grown to 54%. Today, 67% see him as politically liberal including 36% who say he is Very Liberal.

A similar pattern is seen for John McCain. The presumptive Republican nominee was seen as politically conservative by 31% of all voters in December, by 41% in April, and by 67% today. Just 19% say he is Very Conservative.

These numbers reflect much more movement than was seen by the more established candidates running four years ago. While the number seeing Obama as liberal has already shifted by twenty percentage points, John Kerry’s numbers shifted just eight points in a roughly comparable time frame. Kerry was seen as politically liberal by 37% in January 2004 and by 45% in May 2004. By the end of Election 2004, 53% saw Kerry as politically liberal.

McCain’s numbers have shifted even more than Obama’s this year—twenty-six percentage points so far. Four years ago, President Bush was seen as politically conservative by 48% in January and 57% in May. That’s a shift of just nine points. By the end of Election 2004, 64% saw Bush as politically conservative.

It’s worth noting that both Bush and Kerry experienced as much of a shift from May to October as they did in the first part of the year. It is certainly reasonable to assume that more changes are ahead for McCain and Obama. Rasmussen Reports will be tracking this data on a weekly basis to monitor ongoing movement. Premium Members can review crosstabs.

Where do the voters stand in all of this? Thirty-six percent (36%) say they are politically conservative, including 16% who say they are Very Conservative. Thirty-seven percent (37%) say they are politically moderate and 25% claim to be politically liberal. That last figure includes 8% who are Very Liberal.

Compared to four years ago, the number of conservatives is little changed but the number of liberal is up from 17%.

Since clinching the nomination, Barack Obama has enjoyed a nice bounce and currently leads John McCain nationally in the Rasmussen Reports daily Presidential Tracking Poll. Both candidates earn favorable reviews so far from a majority of voters.

Crosstabs available for Premium Members only.