Since President Joe Biden ducked out of the presidential race last month, Vice President Kamala Harris has made steady gains against Donald Trump in most polls.

If she wants that lead to endure past a honeymoon phase, she’ll need to articulate an agenda that appeals to persuadable but as-yet-undecided voters. The positions that will work most effectively just happen to be exactly those the country needs.

No doubt, Harris has reason to hesitate before adopting any such approach. As ever, Trump is his own worst enemy. The vice president might be tempted to let his divisive rhetoric, reflexive dishonesty, personal grievance and flamboyant displays of ignorance do all the work. Setting out where she stands on policy will also mean clarifying — and often contradicting — things she’s said in the past.

Despite the risks, Harris must offer a program. It’s partly a matter of principle: Voters are entitled to no less. But she also needs to convert those who might choose a known quantity over a silent one.

Many of the policies advanced by the Biden administration have been admirable. On foreign policy, the president has been more responsible and coherent than Trump. His commitment to fighting climate change was correct on the merits. The main themes of Bidenomics — the push for good jobs, rising wages and broader prosperity — are well worth supporting.

But Biden too often allied himself with his party’s less enlightened elements. Many of his regulations have made economic progress harder, and his rhetoric has been needlessly hostile to business. As Harris offers her first economic-policy speech in North Carolina today, she should avoid these errors by emphasizing practical results over party-line ideology.

Some examples: The transition to clean energy will go much faster if new investments aren’t bogged down by union-labor and domestic-content requirements. The country is short of workers and needs more immigrants; it also needs a secure border and an orderly process for choosing the people it admits. As a former prosecutor, Harris might offer support for effective policing and insist that criminals are held accountable for their crimes while promising to confront the economic and social conditions that drive criminality. ("Tough on crime, tough on the causes of crime,” as an election-winning politician once said.)

This Harris wouldn’t accuse firms of "price gouging.” She’d call for stronger competition without declaring war on America’s most successful companies. She’d say control of inflation and fiscal responsibility go together, that supporting the Federal Reserve means paying for additional public spending with taxes, not borrowing. She wouldn’t rule out entitlement reform. She’d oblige the better off to pay their fair share but say there’s a limit to what can be squeezed from corporations and the rich without wounding the economy. And she wouldn’t pander, which dispels trust. Promising to exempt tips from income tax, as she has, is a good example of what not to do. (Voters know this creates a gaping new loophole, surrenders revenue they’ll have to pay for and does little to help its intended beneficiaries.)

Some of these positions entail specific policies. Some are matters of signaling, which in a close race is nearly as important. Many voters are dismayed by the prospect of Trump’s second term and would require no more than a competent, intelligible, moderate alternative.

It shouldn’t be beyond Harris to deliver.