AUGUSTA – A decision by Colorado voters to suspend their 13-year-old Taxpayer’s Bill of Rights law has provided fresh ammunition for opponents of a similarly styled spending cap eyed for Maine.

In an effort to help their state bounce back from a recession, Colorado residents voted Tuesday to suspend their tax cap for five years. With 99 percent of the expected vote counted statewide, 575,352 voters, or 52 percent, had approved the suspension, compared with 531,791, or 48 percent, who voted against it.

Colorado has served as the model for a Maine Taxpayer Bill of Rights, or TABOR, that could be on the ballot in 2006. Last month, Mary Adams of Garland submitted signature petitions to the secretary of state to place the spending cap plan before the voters in the form of a referendum question.

While election officials continued efforts Wednesday to verify signatures on Adams’ petitions, some Democratic leaders in Maine predicted Colorado’s decision to give up more than $3 billion in TABOR tax refunds over the next five years should tell Mainers all they need to know about spending caps.

“[Residents of Colorado] are beginning to understand that the TABOR amendment is a very bad idea,” said Maine House Speaker John Richardson, D-Brunswick. “A five-year suspension might as well be forever because after five years, they’re going to realize how much more they’re going to have to do to catch up. They’ve basically strangled their economy, and I wouldn’t be surprised to see them get rid of it all together.”

Gov. John E. Baldacci agreed, saying Tuesday’s vote in Colorado proves spending caps just don’t work.

“They had to suspend it there,” he said. “Whether it’s in Colorado or California, those are great experiences for people to look at when they want to evaluate the plan. They don’t want those things to happen in Maine. While [spending caps] might start out as a popular idea, once people understand the rest of the story, they’ll conclude they don’t want it forced on their state. We should be careful before we try to implement practices that aren’t working in other states.”

The degree of caution Baldacci attached to the proposal is apt to be weighed beyond Maine’s borders. Douglas Bruce, the Colorado anti-tax crusader who wrote the 1992 Taxpayer’s Bill of Rights, said Tuesday’s vote will make spending caps more difficult to pass in California, Kansas, Ohio, Nevada, Oklahoma and Arizona.

Next Tuesday, a proposal to limit state spending goes to the voters in California, and polls already are giving it little chance of passing. Gov. Arnold Schwarzenegger has been urging voters to cap California’s spending and give him the power to cut funding without legislative approval by passing the measure, but opponents there say it would devastate public school funding.

“The establishment [in the states considering TABOR measures] is going to say we [in Colorado] had 13 years of experience with spending limits, and we changed our minds. I’m sorry for their sake, and I’m sorry for our sake,” Bruce said.

The approval of the Colorado referendum allows the state to keep an estimated $3.7 billion over five years that otherwise would have been refunded to taxpayers. A second statewide ballot measure meant to let the state borrow up to $2.1 billion for roads, school maintenance, pensions and other projects narrowly lost. The votes capped a bitter, $8 million campaign in which opponents characterized the two measures as tax grabs by politicians afraid to make tough decisions.

While Maine’s Democratic leaders predicted Colorado’s vote would sound the death knell for Adams’ Maine TABOR assuming it does qualify for the ballot, spending cap proponents maintained Wednesday their effort was very much alive and well.

“That’s just how TABOR works. It lets the voters decide what they’re going to do, and they decided to let the state keep the money for five years and that’s their prerogative,” Adams said. “TABOR is still in place in Colorado and will go back to working as it did five years from now.”

Adams’ assessment of the Colorado vote was shared by Bill Becker, executive director of the Maine Heritage Policy Center, an organization of Republican policy advocates who favor lower taxes in Maine.

Since passage of Colorado’s TABOR in 1992, Becker said that state has experienced strong economic and population growth. Pointing to the Tax Foundation’s ranking of Colorado, Becker said the state was 44th in the annual state and local tax burden index at a rate of 9.2 percent of every $1,000 of income. He said the foundation ranks Maine first in state and local tax burden at a rate of 13 percent.

“There is no doubt that over the 13 years that Colorado’s TABOR has been in place, the law has allowed for economic growth, budget stability and a lower tax burden,” Becker said. “Let’s hope that if Mainers approve TABOR, that the state will experiences these same benefits.”

MaryEllen FitzGerald, owner of the Portland-based Critical Insights polling group, said that should Adams’ spending cap get on the Maine ballot, Colorado’s experience is unlikely to be a factor at the polls.

“I don’t think Colorado has ever been a bellwether for Maine,” she said. “That won’t stop spending cap opponents from jumping on this as evidence of something that should be considered. We’ve seen situations like that before, and they do not typically influence Maine voters.”

The Associated Press contributed to this report.