Gov. Scott Walker of Wisconsin has officially announced his campaign for president on Monday, making him the last expected major Republican candidate to enter the race. Walker has spent the past four years locked in battles with political opponents in his home state — he’s won three elections in four years — and his success has led many observers to put him next to Jeb Bush in the top tier of a packed GOP field. How is a 47-year-old GOP governor of a small, generally liberal Midwestern state a presidential frontrunner? Walker became famous shortly after he took office in 2011, when he stripped public employees of their collective-bargaining rights and effectively crushed public unions in Wisconsin. The move inspired tens of thousands of people to stream to the State Capitol for weeks of massive protests and rallies against the proposal. It also led to a recall election in 2012, which Walker easily survived. Since then, the former Milwaukee County Executive has completely changed almost every aspect of Wisconsin. He repealed a law that made it easier for victims of wage discrimination to take cases to court; he’s rebuffed attempts to raise the state’s minimum wage from $7.25; he signed laws that greatly restricted abortion access, including a 20-week abortion ban that includes no exceptions for rape or incest. Just since his reelection, he has signed right-to-work legislation and a budget that eliminates the state’s living wage protections. He also cut hundreds of millions of dollars from Wisconsin’s university system, eliminated a waiting period for gun purchases, and has supported ending workers' right to a weekend. All these policy decisions, along with his vocal opposition to last month's Supreme Court’s same-sex-marriage ruling, make Walker one of the most conservative candidates running, but his three campaigns prove that even with such far-right ideas, Walker knows how to appeal to a lot of voters. But not all of them. Democrats and women's-rights, civil-rights, and low-wage-worker activists have struggled to limit the impact of Walker's policies and, now that he's trying to go national, to educate the public on what his time in office has meant for the people of Wisconsin. "That Gov. Walker is announcing today he is running for another political office is little surprise. He’s politics incarnate — having spent almost his entire adult life doing or saying whatever he needed to win an election," Jenni Dye, research director of One Wisconsin Now, a progressive advocacy group, told us in an email. "While one of the most divisive politician our state has ever seen touts his willingness to fight to the right-wing electorate he’s currently courting, the people of Wisconsin are left to live with the fallout from the cronyism, corruption, and incompetence of his administration." Walker's ability to speak to conservative voters and business interests has already given him an advantage over many of his opponents. Since he was first elected, Walker has had the ear of Charles and David Koch, the billionaire conservatives who have dedicated themselves and their fortune to promoting right-wing causes. They haven't officially endorsed him in the presidential race yet, but they have appeared with him at fundraisers, and if he wins the nomination, their close relationship will be a huge help for the Wisconsin politician. One topic of attack that Walker's opponents are likely to steer clear of isn't a political position but a question of qualifications. Walker never finished college — he left during his senior year — but at a time when so many people are struggling to afford higher education, attempts to paint his lack of a degree as a bad thing have backfired. Walker has been one of the top few candidates in every early poll, and he’s planning a massive push in Iowa this weekend to boost his chances against Jeb Bush — who also recently announced his campaign and whose Super PAC has raised a total of $114 million. The initial Republican debate will be held on August 6, which will be the first time for Walker, Bush, and the eight other top-ranking candidates to introduce themselves to the nation as a whole.