A little blue book is turning up in mailboxes, an election season ritual that has often spurred ferocious battles among Colorado politicos.

The state will finish mailing 1.7 million voter guides - known as the "Blue Book" - to registered voters by Friday.

The Colorado Constitution requires the legislature's nonpartisan research staff to prepare a handbook for voters that explains the arguments for and against statewide ballot questions. This year's book is all about Referendums C and D.

Many people believe the Blue Book has a big impact.

"The Blue Book comes up a lot in conversation," said Pete Maysmith, executive director of Colorado Common Cause. "It's used a lot. You know it's important if everyone puts so much energy into it."

Those on opposing sides of ballot questions often square off like pit bulls who missed breakfast when hearings are held to discuss the language in the Blue Book. This year was no different.

"It's this year's government-sponsored, pro-tax advertisement," said Jon Caldara, a leading opponent of the referendums.

Caldara specifically objects to the statement that the referendums are not a tax increase, and says the book fails to include all the legal language from Referendum D.

Referendum C would suspend state spending limits for five years, allowing lawmakers to spend an estimated $3.7 billion they otherwise would have refunded to taxpayers. Referendum D would let the state borrow up to $2.1 billion against that money to start road and school construction right away.

In past years, it was liberals who fulminated against the Blue Book. In 2004, under pressure from the tobacco industry, the legislature changed language describing the impact of a proposal to raise the tobacco tax to suggest it might harm funding for local police and fire protection.

"Why don't we just say that if you vote for this your house will burn down and be burglarized," state Sen. Ken Gordon, D-Denver, said at the time.