VIRGINIA GOV.-ELECT Terry McAuliffe, who faced a barrage of allegations as a candidate over his past conduct in business, will take office in January in a state reeling from its worst public ethics scandal in years, replacing an incumbent who faces possible indictment. As a top priority, Mr. McAuliffe (D) should throw his weight behind a package of reforms that would add muscle to flaccid ethics rules.

Mr. McAuliffe hinted Wednesday that ethics would feature prominently in his agenda, announcing that upon taking office he would sign a pledge that neither he nor members of his family would accept gifts worth more than $100. That’s a modest gesture but only a start.

At the heart of Virginia’s ethical dysfunction is an anything-goes approach to money in politics. In a state with no limit on campaign donations, no public ethics commission and Swiss-cheese laws governing disclosure of gifts from favor-seeking constituents, ethics reform is a critical step to wipe away the tarnish left by Gov. Robert F. McDonnell (R), whose acceptance of lavish gifts from a businessman remains under investigation.

Mr. McAuliffe, who wrote the book on creative ways of melding money and politics, may seem an unlikely leader to clean up a state that has suffered from lax rules. According to exit polls conducted Tuesday, half of his own voters said neither he nor his Republican opponent, Ken Cuccinelli II, has high ethical standards.

That gives Mr. McAuliffe an opportunity to prove the conventional wisdom about him is wrong. In doing so, he could also strike a blow for bipartisanship at the outset of his four-year term.

Among the Republicans who have proposed or acknowledged the need for new ethics rules in the wake of the McDonnell scandals are Mr. Cuccinelli, Lt. Gov. Bill Bolling (R), House Speaker William J. Howell (R-Stafford) — and even Mr. McDonnell himself, who has pledged to submit a package of reforms before he leaves office.

Mr. Bolling has offered a specific package of fixes, including a total $250 ceiling on gifts to any elected official; more rigorous disclosure of gifts, income, investments and loans; and an outright ban on the personal use of campaign funds. That would hamstring lawmakers such as Del. Timothy D. Hugo (R-Fairfax), who blithely charges gasoline, fast food, groceries and other routine daily expenses to a campaign committee funded largely by deep-pocketed special interests.

Last year, a nonpartisan group led by the Center for Public Integrity gave Virginia an F in a report card measuring the risk of corruption based on existing laws and institutions. One of eight states that received a failing grade, Virginia ranked 47th out of 50 nationally and got especially poor marks for ethics enforcement, disclosure of lobbying activities and public access to information.

In the absence of legislative action backed by Mr. McAuliffe, the tarnish to Mr. McDonnell’s reputation would become a stain on Virginia’s as well.