PHOENIX — Backers of what could be the largest tax hike in state history filed suit Wednesday to put their proposal back on the November ballot.

Attorney Charles Blanchard acknowledged in legal papers filed in Maricopa County Superior Court that some of the petitions turned in to the Secretary of State’s Office do not technically comply with all of the legal requirements for initiatives. But he said the mistakes are technical.

More to the point, he said many of the errors appear to be with the way the signatures of the petition circulators were notarized. Blanchard said that should not invalidate the will of the people who signed the measure and want to vote on it.

He also said the Secretary of State’s Office and the Maricopa County Recorder’s Office improperly rejected various other signatures.

Blanchard is hoping to convince Judge Thomas Dunevant III to rule that enough of the disqualified petitions and signatures should be counted to get the count of valid names up to 95 percent of the 153,365 legally required to put Proposition 203 on the ballot. That 95 percent figure, extrapolated from a random sample, is considered sufficient because there is not enough time before the ballots have to be printed to check the validity of every signature.

The measure would boost the state sales tax rate from 5.6 percent to 6.6 percent to raise $42.6 billion during its 30-year life. Most of the money would go to new highways and roads, with some set aside for mass transit projects ranging from vanpool service to a train between Tucson and Phoenix.

Gov. Janet Napolitano, who backs the tax hike, said Wednesday that she is confident the courts will put the measure on the ballot. And she said it is important.

“It’s something Arizona really needs,” she said. The governor said transit improvements are necessary to deal with not only current traffic congestion but the growth that will occur in the next three decades.