Brown Courts Rebellious Wisconsinites : Campaign: He expresses optimism for success among state’s independent voters. But questions arise about his 13% flat-tax proposal.

Former California Gov. Edmund G. (Jerry) Brown Jr. brought his insurgent, anti-Washington campaign for the Democratic presidential nomination to Wisconsin on Thursday, seeking support from the state’s historically independent-minded voters.

Once on the ground, however, Brown was greeted by probing questions about his 13% flat-tax proposal and his reaction to the endorsement Arkansas Gov. Bill Clinton received during the day from Iowa Sen. Tom Harkin, who ended his Democratic presidential campaign earlier this month.

Brown was unfazed by the questions about his tax plan and undeterred by Harkin’s decision, vowing to press on with building the grass-roots support that has propelled his campaign.

“Connecticut is only the start,” Brown said, referring to his upset defeat of Clinton in that state’s Tuesday primary.

On the heels of that victory, Brown plans to split his campaign time the rest of this week between New York and Wisconsin, which hold primaries April 7. In Wisconsin, 82 delegates are at stake, while 244 are up for grabs in New York.

Clinton has been focusing his attention on New York, where he has been blasting Brown’s plan for a flat tax as one that would benefit the rich at the expense of the middle class and the poor.

Perhaps as a result, Brown spent a good deal of his day defending his idea to simplify the nation’s tax structure by imposing a 13% flat tax on personal income and a similar value-added tax on manufactured goods.

At a labor rally in Racine, Wis., John Ostrom stood outside the union hall and helped hold up a sign that read, “Flat tax fraud from the man on the moon,” a reference to the “Gov. Moonbeam” moniker Brown’s critics once tagged him with.

“I’m not making it now because I’m earning minimum wage,” said Ostrom, a 35-year-old apprentice mechanic. “Why should I pay the same rate as (President) George Herbert Walker Bush?”

Tim Reeves, 35, who held up the other side of the sign, said he came to hear Brown and would probably vote for him in the primary. But he added that he does not believe Brown’s tax proposal was very well thought out.

“I don’t know what he means, and I want to better understand what the tax idea would do for me,” Reeves said.

Brown, responding to questions about Harkin’s endorsement of his rival, accused the former candidate of shelving the angry-man identity he used during his aborted campaign and closing ranks with Clinton and other members of the Democratic Establishment.

Relishing his self-described role as the only “true outsider,” Brown promised to fight a lonely battle to reform the Democratic Party from insiders who he claimed “are trying to promote a one-candidacy, restricted good-old-boy operation.”

“When you run a frontal assault on what you call a decrepit and corrupt status quo that no longer serves the American people, you can’t be surprised if people in that neighborhood band together in a mutual protection defense one more time,” Brown said.

Ruth Ann Fennel, a 53-year-old high school teacher, said she had supported Harkin but was “upset” by his decision to endorse Clinton.

She added: “I think the people of Wisconsin are traditionally liberal, open, rebellious and labor-oriented. They will respond to Brown because they don’t like for powerful people to tell them what to do.”