Democratic presidential candidate Barack Obama plans to visit Denver and Fort Collins on Sunday in his third trip to Colorado since his party's national convention in August.The Illinois senator will hold rallies for early voting in Civic Center Park in Denver and at Colorado State University's Oval in Fort Collins, Obama's campaign said.The Denver rally begins at 11:30 a.m. The rally at CSU is scheduled to begin at 3:30 p.m.Both campaigns have been picking up appearances in Colorado with early voting under way. Colorado is a battleground state with nine electoral votes that both campaigns are eager to win.Republican candidate John McCain is holding rallies Friday in Durango and Denver, where he will be joined by former Denver Broncos quarterback John Elway. McCain also plans to talk with small business leaders in Colorado Springs.Sen. Hillary Clinton will campaign for Obama at a stop in Aurora on Friday.