In formally rolling out his candidacy yesterday, the retired Philadelphia businessman proposed to change state law by requiring state or local officeholders to step down before seeking any new office.

That was one of a package of ethics proposals that Knox introduced in a video ad on newspaper Web sites, and in an e-mail blast that his campaign said went to 800,000 Pennsylvanians.

If Knox's proposal were already law, it would nix the candidacy of Dan Onorato, the Allegheny County executive. It would eliminate Joe Hoeffel, a Montgomery County commissioner. It would knock out Jack Wagner, the state auditor general. And it would nuke Chris Doherty, mayor of Scranton. Knox, 68 and never elected to any office, would be the only Democrat left standing.

Isn't that "an incredibly self-serving position to take?" he was asked by a participant in a chat conducted on his Web site yesterday, a chat his campaign said was open to all.

"It is only self-serving because I am the only one not looking to build a political resumé," he replied.

He focused his criticism not on Democrats but on Tom Corbett, the leading GOP candidate for governor. As state attorney general, candidate Corbett oversees the so-called Bonusgate investigation of state legislators and their staffers.

"Our attorney general has been accused of using his power to prosecute persons in order to enhance his run for governor," Knox said in his Web chat. "That charge may be unfair, but it creates a terrible perception among voters that government decisions are not being made in the public interest."

Republican U.S. Rep. Jim Gerlach of Chester County is also a candidate for governor. As a federal official, he would be exempt from Knox's proposal.

Knox, who spent $12 million of his own money in a 2007 bid to win the Democratic nomination for Philadelphia mayor, casts himself as the outsider, the candidate who owes nothing to anyone and is free to institute changes that lobbyists and politicians may not like.

His personal story is compelling. He left school at 16 when his father was hurt on the job. He served in the Navy, sent checks home, and became a door-to-door salesman.

He earned his GED and made a fortune revitalizing failing companies and selling them. He said yesterday he no longer holds majority interest in any company.

He was appointed deputy mayor during Gov. Rendell's tenure as Philadelphia's chief executive in the 1990s.

On the first formal day of his campaign, Knox went at hard issues, taking all sorts of questions from online particiants and reporters alike. The proposals he offered include ideas that have been batted around in Harrisburg for decades.

He proposed to halve the legislature, now America's biggest full-time assembly with 50 senators and 203 House members. He proposed that judges be appointed, not elected.

He proposed to eliminate the so-called WAMs ("walking around money") that legislators spend on home-district projects. The state's new budget limits such grants.

And he suggested a $500 cap on individual giving to state and local campaigns. Pennsylvania is one of the few states that have no limit. Such a cap would also benefit Knox, who vowed to spend "what it takes" to be elected governor.

"Maybe the wealthy have an advantage, in that they do not have to take contributions from special interest groups," he told reporters. "And that is good. Usually, the wealthy cannot be bought."

With his emphasis on ethics, Knox was asked about his September admission to the Philadelphia Board of Ethics that he had broken the rules in his mayoral run.

In 2007, radio ads attacking then-candidate (now mayor) Michael Nutter were attributed to the nonexistent Alliance for Better Christians. Knox later admitted his campaign was behind the ads.

"It was a reporting error, is all it is," he said yesterday, adding that he didn't know about the ads until after his campaign aired them. "If I had seen that ad, I never would have run it."

He promised not to run negative ads against the Democrats in the governor's race - unless his rivals fire first.

Knox's biggest obstacle may be his home town. Rendell was the only Philadelphian elected governor in a century. And now his approval ratings are at a low ebb.

One of Knox's online quizzers yesterday had a screen name suggesting a Pittsburgh Steelers fan. "You are a Philadelphia liberal - guns, abortion, taxes," the participant said. "I like what you say on reform, but what will you do to understand Western Pennsylvania voters and not be another Ed Rendell?"

Daniel Shea, a political scientist at Allegheny College - in far northwestern Pennsylvania - noted that a candidate as rich as Knox may not need many western votes in a primary if he can handily win his populous home area.

"I think he's trying to distance himself from Rendell," Shea said. "That's pretty clear."

Tom Knox

Age: 68

Residence: Rittenhouse Square

Party: Democratic.

Education: Dropped out of Roman Catholic High School after 10th grade; earned GED in Navy.

Business experience: Former executive officer, United Health Care of Pennsylvania; former executive of other banking and insurance companies going back to 1967.

Politics and government: Deputy Philadelphia mayor for management and productivity, 1992-93; unsuccessful candidate for mayor, 2007.

Family: Married to Linda Knox. Two adult sons, Brandon and T.J.