Complex voter demographics and controversial issues are turning Colorado into a battleground state in this year's upcoming election.

Although the Democratic National Convention received a warm welcome in Denver, the state gave its Electoral College votes to George W. Bush in 2004.

The state has 9 votes to offer this year, and Democrats have posted big gains in Colorado. The Associated Press reported that Democrats out-registered Republicans, bringing in nearly 13,700 new voters to the under 4,100 new registrations for Republicans.

However, Republicans claim the largest voting bloc in Colorado. In June, they were trumped by unaffiliated voters who still trail closely behind, marking the first time in almost 20 years that independents held the largest voting demographic. The numbers according to AP are as follows:

1. Republicans: 1,024,500
2. Unaffiliated:1,022,400
3. Democrats: 946,200

Colorado demographics have been shifting in the Democrats favor. The Hispanic population in the state has grown since the previous election, and polls suggest that group is largely left-leaning.

Colorado poses an interesting problem for candidates hoping to make appeals to voters on socially controversial issues. Several hotly contested measures have made their way onto the Nov. 4 ballot.

Colorado, along with South Dakota and California, is gearing up to decide the fate of abortion with a vote on a measure that would put the beginning of a human life at "the moment of fertilization." This could pose a clear challenge to abortion writes as defined after Roe vs. Wade.

Voters will also be asked to look at other hotly debated issues, such as removing affirmative action from state universities, tweaking workers rights and income taxes.