SALEM, Ore. — State election officials are using a team of observers to monitor the activities of signature-gatherers who are trying to derail a $733 million tax hike passed by the 2009 Oregon Legislature.

This is the first time the state has hired a team of people to do random spot checks of petition campaigns. In the past, state election investigators have responded on a case-by-case basis to complaints about problems in initiative or referendum campaigns.

A spokesman for business groups trying to overturn the tax hikes says the Democratic-controlled Legislature decided to hire up to 10 investigators with the goal of slowing down and thwarting the anti-tax petition drive.

The state already has a system in place in which it verifies petition signatures to make sure they are those of registered Oregon voters, said Pat McCormick, spokesman for the group Oregonians Against Job-Killing Taxes.

McCormick said the state’s newly hired investigators have approached petitioners, “asking them questions, slowing them down and taking up time that we are paying these people to collect signatures.”

“Notwithstanding this questionable use of taxpayer money, we are confident we will qualify for the ballot,” he said.

But a spokesman for Oregon House Speaker Dave Hunt said hiring the observers is part of a long-term effort by the state to gain better oversight of initiatives and referendums in general to avoid potential fraud or abuse.

Lawmakers want to ensure that signature collectors for the anti-tax drive and any other ballot measures are following all the rules, Geoff Sugerman said.

The $135,000 to pay for the 10 observers was tucked into a final catch-all budget measure that passed in the closing hours of the 2009 legislative session.

Deputy Secretary of State Barry Pack said seven of the investigators already are in the field and a few more probably will be added soon to look for any irregularities or petition carriers not following all the laws.

“We are out there checking places where you might expect people to be circulating petitions, like shopping centers and county fairs,” Pack said. “Our job is to make sure that anything that gets on the ballot gets there legitimately” with valid signatures.

So far, he said, the observers have found no problems in the way paid and volunteer petition carriers have been rounding up signatures for the anti-tax measures.

He said the observers would monitor signature-gathering efforts for other ballot measures in the coming year, although most of the activity at present surrounds the efforts to overturn the Legislature’s income tax increase on corporations and higher-income people.

Forcing a statewide vote on those would require more than 55,000 valid signatures. If McCormick’s group can gather that number, the tax increases would be put to a statewide vote in a Jan. 26 special election.

Business groups backing the referendum effort say the tax increases will slow Oregon’s economic recovery and cause more job losses.

Tax supporters, led by the union-funded Defend Oregon coalition, are preparing a campaign to persuade voters to support the increases as a matter of tax fairness and protecting schools and vital services from budget cuts.