Sen. Barack Obama campaigns in Southern Nevada for the second weekend in a row (Getty Images)

“You don’t need to boo. You just need to vote,” Sen. Barack Obama told his supporters who booed when he mentioned his Republican rival, Sen. John McCain, this morning at a campaign rally in Henderson, Nevada.

Early voting in Nevada and Colorado — where Obama is scheduled to appear this afternoon — ended Friday, and Obama looks to be in good shape in both swing states. But he cautioned the race isn’t over and implored his supporters to get out the vote on Tuesday.

“Don’t believe for a second this election is over.” he said. “We have to work like our future depends on it in these last few days, because it does.”

More than 40 percent of registered Nevadans cast early ballots. Clark and Washoe counties, which together comprise 87 percent of all registered voters in the state, are the only counties to report on the party affiliation of registered voters. The Las Vegas Review-Journal reported that 52 percent of early voters were registered Democrats and 31 percent were registered Democrats in those counties. Exit polling of more than 15,000 early voters shows Obama getting 53 percent to McCain’s 44 percent, according to the Review-Journal. The polling firm’s findings suggest Obama has widened his lead among early voters in the past week, since results through last Sunday gave Obama a slimmer 50 to 48 lead.

More than half of Colorado voters will have cast ballots before Tuesday, either by mail or at early voting sites. A poll released Thursday showed Obama leads McCain among Colorado early voters 59 to 41 percent. The poll found that among likely voters who hadn’t yet cast their ballots the candidates were tied at 46 percent each.

Obama’s last stop in Nevada before the election — his 20th in the Silver State — marked the second weekend in a row the candidate hit this Western battleground. McCain hasn’t stepped foot in Nevada since early August, but will join runing mate Gov. Sarah Palin on election eve.