A University of Illinois analysis of public opinion poll data in each of the 50 states and the District of Columbia indicates that Democratic presidential candidate Barack Obama is continuing to build his electoral vote lead over Republican candidate John McCain.

During the 10-day period between an Oct. 2 analysis and Oct. 13, Obama’s electoral vote count rose from 338 to 353. During this same period, McCain has lost 31 electoral votes as his total dropped from 200 to 169. (A total of 270 electoral votes are needed to be elected president.)

The analysis conducted by researchers at the University of Illinois Institute of Government and Public Affairs is based upon the results of public-opinion poll data. That data is applied to formulas designed to approximate the electoral vote totals.

Analysis of data available through Oct. 12, following the economic downturn in September, finds McCain losing ground in both key battleground states, as well as slipping in states that have been part of the GOP base in 2000 and 2004.

“While a period of debates tends to freeze voter support for candidates until after all of the debates have ended, the economic events appear to have trumped the debates in motivating voters to make and or change their choices,” said IGPA Senior Fellow Michael R. Cheney, who has conducted the research with undergraduate student Crystal Olsen.

In a second analysis, which included margin of error and poll reliability, Obama’s electoral vote count is projected at 252, while McCain has 146 projected electoral votes. There are 146 electoral votes currently in states that are deemed statistical dead heats.

“An analysis of the electoral map shows that normal red state/blue state patterns of 2000 and 2004 are being redrawn and are shifting and a new pattern beyond 2008 may be emerging.” said Cheney, who also is co-director of IGPA’s Center for Technology and Public Policy.