MADISON (AP) - One of the most moderate Republicans in the Wisconsin state Legis-lature, and the only Repub-lican to vote against Gov. Scott Walker's union law known as Act 10, will retire rather than take on a more conservative challenger.

State Sen. Dale Schultz, of Richland Center, announced Monday that he would retire at the end of his term this year, saying "there's simply more to life than being senator." Schultz's southwestern Wisconsin seat is one of 17 up for election this year, but one of the few considered competitive.

His senate district includes part of Green County, including the city of Monroe, and most of Lafayette County.

Schultz, 60, will have served 32 years when he retires. He said he was not retiring from public life, but declined to say what he planned to do next.

Republican Rep. Howard Marklein, of Spring Green, announced in April that he was running for the seat after Schultz cast a series of votes that rankled GOP leadership, including opposing a bill that loosened environmental regulations to ease siting of an iron ore mine in northern Wisconsin.

Marklein issued a statement saying Schultz had "dutifully served his constituents" and that he will be missed by both Republicans and Democrats. But Schultz said he would not endorse Marklein, saying he was out of step with the views of people in his district.

Democrat Ernie Wittwer, who worked 24 years for the state Department of Transportation, is also running. Democrats have targeted Schultz's district as a place where they could gain ground in the Senate, which is controlled by Republicans 18-15.

Schultz was first elected to the Senate in a special election in 1991 after serving nine years in the Assembly. He rose in the ranks, serving as majority leader from 2004 to 2006.

But in recent years, as Senate Republicans have become more conservative, Schultz's independent streak has upset party leaders and spurred Marklein's unusual primary challenge.

Schultz was the only Republican in the entire Legislature in 2011 to vote against the union law that limited collective bargaining for most state workers to wage increases no greater than inflation. His vote angered Republicans on that issue that led to recall elections against 13 senators and Gov. Scott Walker.

He also went against Walker and Republicans on other issues, including voting last year against loosening environmental laws to ease the opening of the northern Wisconsin iron ore mine.

Schultz was also the only Senate Republican to vote against Walker's budget last year.

Schultz fueled suspicion that he might not run again after raising only $684 in the first six months of last year, while Marklein brought in $116,000.

Schultz cited the creation of the independent WisconsinEye television network, which broadcasts legislative floor debate, committee hearings and other government-related programming, as one of his greatest accomplishments.

He bemoaned the increase of special interest money in politics, saying "compromise has given way to partisan conformity, and that's not something in which I'm willing to participate."

Schultz is the third-longest-serving member of the Senate to announce his retirement at the end of this year. Sen. Tim Cullen, a moderate Democrat who toured the state with Schultz to call for more bipartisanship and compromise, is retiring, as is Sen. Bob Jauch, a Democrat from Poplar.

The three of them will have served a combined 80 years in the Legislature when they retire at the end of the year.