MADISON, Wis. (AP) -- A Wisconsin lawmaker could face expulsion after police arrested him Wednesday for driving while intoxicated -- his third such offense in less than a year.

Police pulled Rep. Jeffrey Wood over after a citizen reported an erratic driver and officers saw his 1998 Buick Skylark swerve in traffic and drive over a curb in a business district on the north end of town, said Police Sgt. Scott Holum.

Prescription medication found on Wood, an independent from Chippewa Falls, was believed to be the source of his intoxication, Holum said. A preliminary breath test showed 40-year-old Wood did not have alcohol in his system, but he failed a field sobriety test, he said.

Wood was taken to a hospital to draw blood for drug testing and then transferred to the Monroe County Jail, where he was booked Wednesday evening. He was facing charges of operating under the influence of an intoxicant and bail jumping.

Wood's attorney, Tracey Wood, who is no relation, said she had not spoken to the lawmaker and had no comment on his latest arrest.

One week earlier, Rep. Stephen Nass, R-Whitewater, introduced a resolution seeking to expel Wood from the Assembly because he had already been arrested twice in the last 10 months.

Nass aide Mike Mikalsen said Democrats who control the Assembly had been attempting to negotiate a lesser punishment, such as a censure, for Wood in recent days.

"Any possibility of that is now unacceptable to Rep. Nass based on what happened on the streets of Tomah this afternoon," Mikalsen said. "Rep. Wood is a menace, a threat to public safety and can no longer, in Rep. Nass's eyes, serve honestly or effectively in the Assembly.

"There is now no choice but to expel Rep. Wood and actually do it rather soon."

Wood was elected to the Assembly in 2002 and served three two-year terms as a Republican, but ran for election as an independent last year. He became the first independent elected to the Wisconsin Legislature in decades but has been voting with the Democrats on budget matters.

Two-thirds of lawmakers would have to agree to expel Wood, who has so far ignored calls to resign. Only one lawmaker has been expelled in Wisconsin history, and that happened in 1917.

Wood, who represents a northwestern Wisconsin district, said last month he was getting treatment after being arrested for operating while intoxicated and inattentive driving.

Police say he had taken a large quantity of cough syrup and prescription drugs. During that arrest, police found a prescription bottle of Lorazepam, an anti-anxiety drug, with seven pills left inside. The 45-pill prescription had been filled only a day earlier.

Wood was also arrested in December and charged with third-offense drunken driving and possession of marijuana and drug paraphernalia. He had crashed into a highway sign and a state trooper spotted him urinating on the side of Interstate 90 in Columbia County.

A search of Wood's vehicle turned up two small bags of marijuana and a pipe. A breath test showed Wood's blood alcohol level was nearly twice the legal limit. Records show Wood was arrested for drunken driving in 1990 and 1991.

Wood has not been convicted in any of the recent cases and contends the December search of his vehicle was illegal because the state trooper did not have a warrant.

(Copyright 2009 by The Associated Press. All Rights Reserved.)