DENVER – Former President Bill Clinton used a pair of appearances in Colorado Tuesday to shore up support for President Obama in a state that has emerged as one of the most competitive battlegrounds this fall.

“I am telling you not to go back and relive the past,” Clinton told a rally at a Denver high school one week before Election Day.

Clinton’s visit to the Denver area – he also spoke in Adams County, just north of the state capital – came on the same day Obama had planned to campaign in Colorado Springs. But Obama canceled his visit, along with stops in Ohio and Wisconsin, to oversee the response to Hurricane Sandy.

Clinton, who presided over an economic upswing in the 1990s, touted his own record and made the case for Obama’s fiscal policy, which has become a focal point of the campaign.

“The president’s budget plan is way better,” Clinton said. “The president’s plan honors our values and meets the test of arithmetic.”

Just four years removed from the bitter Democratic primary between Obama and Hillary Clinton, Bill Clinton has evolved from an angry antagonist of Obama to staunch backer and prolific campaigner. In September, he delivered the nominating address for Obama at the Democratic National Convention in Charlotte, N.C.

In Denver, Clinton did not disappoint in his newfound role as the campaign’s substitute star attraction, delivering harsh attacks on Republican Mitt Romney, who polls show is tied or leading Obama in Colorado.

“The essential argument of Gov. Romney is: ‘Hey, I look like a president, I act like a president, I’ve proved I can change my message for any circumstance, so elect me, and I’ll claim the credit,’” Clinton said during his appearance before an estimated crowd of 2,000.

The Republican National Committee said Clinton’s visit reflected the desperation of Obama.

“With one week to go until Election Day, Bill Clinton’s visit to the area is illustrative of a very worried Obama campaign,” spokeswoman Ellie Wallace said in a statement. “Colorado is a state that Obama won by 9 points in 2008, but today, his standing with Colorado voters couldn’t be more different.”

Clinton acknowledged Colorado’s potential for a starring role on Election Day.

“Colorado could decide this election,” Clinton said. “It’s a close election. It shouldn’t be, but it is.”

Though Superstorm Sandy briefly slowed the campaign, both sides have made it clear that Colorado will be in their sights as they return to the campaign trail. Rep. Paul Ryan, Romney’s running mate, is due in Greeley, northeast of Denver, on Thursday. Later that day, Obama will visit Boulder, a Democratic stronghold. Romney will travel to the Denver area on Saturday.