Ms. Sirleaf may also have weakened her own hand by governing well. Dictators of years past ruled by fiat or by weighting nothing-for-nothing bargains with a simple, loaded question: “You have a daughter, right?” Ms. Sirleaf removed brute force from Liberia’s political playbook. Political violence has abated. The rule of law and respect for the legislature’s constitutional role as a counterweight to the executive have been restored. But these changes have also emboldened political competition, complicating other types of reform.

No longer fearing reprisals for opposing the president, politicians have newfound influence. Lawmakers have taken to holding legislative items hostage, making material demands when the time comes to pass budgets, allocate money for schools, confirm political appointees or enact laws.

Her leverage limited by the tools of democratic governance, Ms. Sirleaf used “cash violence,” in Liberian slang, or the persuasive powers of the purse, to bring political competitors to her side. She gave or withheld government positions and contracts, and used off-the-book inducements.

Such structural problems resist easy fixes and the odds rarely favor reformers, but at certain moments — such as during political transitions — narrow windows of opportunity open. Mr. Weah is in such a moment, because Liberia, while still fragile, has passed through the period when restoring stability had to be an absolute priority. He can now turn to smaller technical fixes that did not even appear on Ms. Sirleaf’s radar.

For starters, Mr. Weah could set new expectations for greater accountability by promptly issuing an executive order asking all government ministries and agencies to publish their monthly expenditures. It’s a simple step, but it could have an outsized impact on combating government fraud by opening spending to public scrutiny.

Mr. Weah should instruct the finance ministry to allocate funds only to government entities with an approved procurement plan. Government contracts for goods and services — which, officials have told me, can account for up to 50 percent of the total budget — offer easy opportunities for graft. Just 41 percent of government entities currently have such plans even though those are required by law. Tying funding to compliance would change this practice is no time.

The new president should also ask the General Auditing Commission to examine the legislature’s 2018 expenditures and legislators’ assets. Remarkably, the National Assembly has never had to account for its spending despite persistent allegations of corruption. Giving legislators a full year’s warning would allow them to correct any problematic behavior; past practices should be ignored, as looking into them would be a political nonstarter. Calling for oversight of this kind would have been too contentious in the past, but the new Speaker of the House — the third-highest position in the country — is an ally of Mr. Weah’s and has previously said he would support such a move.

Mr. Weah faces a moment of consequence and a rare opportunity to build on Ms. Sirleaf’s successes. She brought Liberia back from the dead. Now it’s his turn to nurture the country’s fledgling institutions by taking on its coercive, corrupt political culture.