DENVER — Sen. John McCain opened up a fresh line of attack against his presidential rival in Colorado yesterday, saying Sen. Barack Obama's election would give Democrats unchecked authority over the nation's purse strings.

"The answer to a slowing economy is not higher taxes, but that's exactly what's going to happen when the Democrats have total control of Washington," he warned, while also taking a swipe at Rep. Barney Frank, D-Mass., for suggesting that taxes and spending may need to be increased to deal with the nation's economic crisis. "When he says that, quote, there are, quote, 'a lot of very rich people out there whom we can tax,' it's safe to assume that means you," McCain said.

McCain spent the day in Denver, Colorado Springs and Durango, campaigning in a traditionally Republican state where Obama is leading in the polls and has been flooding the airwaves with advertisements. McCain was accompanied by John Elway, a former Denver Bronco quarterback legendary for fourth-quarter heroics, who told the Denver crowd that he "knows a thing or two about comebacks" and expressed confidence that McCain would defy predictions that he will go down to defeat here.

Obama, who was off the campaign trail yesterday visiting his ailing grandmother in Hawai'i, has worked to deflect his rival's attacks, insisting that in his administration taxes would go up only for people making more than $250,000.

In a conference call, senior aides to Obama described an electoral map that heavily favors their candidate and an organizational juggernaut aimed at sweeping the battleground states that are still up for grabs.

The best news for Obama, campaign manager David Plouffe said, is that McCain is not seriously threatening in any state that voted for Democratic Sen. John F. Kerry in 2004.

McCain is making an aggressive run at Pennsylvania, but Plouffe pointed out that Democrats hold a 1.2 million voter-registration advantage in the state, double the 2004 edge.

The "cold, hard numbers," as Plouffe put it, are this: McCain would have to win 15 percent of the Democratic vote, 95 percent of the Republican vote, and 60 percent of independents to carry Pennsylvania on Nov. 4.