NOW THAT President Biden is in the Oval Office, it may be tempting to forget the election-law failings we saw in 2020. That would be a historic mistake; those weaknesses must be addressed before the next presidential race. Many Republicans, meanwhile, want to take the wrong lessons from 2020, making it harder to vote rather than easier and safer. This, too, would be a tragic error.

The needed reckoning should be thoughtful, extensive and ambitious — and it will cost money. The National Task Force on Election Crises, a cross-ideological group of more than 50 experts on elections, security, public health and other relevant areas, released a report in January that offers a good starting point.

The task force noted that, despite the lies that former president Donald Trump spun, the 2020 vote itself went remarkably well. Amid a pandemic, the nation smashed turnout records. Though some people faced massive lines, most did not. Voting machines were much more secure than in previous years.

This success was in large part due to the nimble response of election officials who had months to prepare for a pandemic election. Expanding vote-by-mail and early-voting options was essential. Experimenting with drop boxes and curbside voting made casting a ballot easier than ever. Stepped-up recruitment of polling workers ensured adequate staffing in case some called in sick. These changes did not imperil election integrity; on the contrary, credible election observers deemed the vote free and fair. An overwhelming lesson of 2020 is to maintain and expand on these shifts.

Better absentee ballot tracking systems would make mail-in voting more secure and increase confidence in the process. Allowing election officials to begin processing absentee ballots well before Election Day would slash the time it takes to get results and provide voters more opportunity to clear up problems with their paperwork. Stepping up polling worker recruitment — and not just of retirees who are more vulnerable during a pandemic — would ensure polling places can function smoothly. Conducting statistically sound post-election audits of paper ballot records would add another layer of protection. Dedicated state and federal money for election needs would enable reform.

The worst problems came after Election Day, when Mr. Trump and other Republicans mounted a campaign to overturn the vote based on a torrent of disinformation. The cracks in the system they tried to exploit must be addressed. Federal laws governing presidential transitions and electoral vote counting must be rewritten to cut opportunities for officials to deny election results in bad faith. State secretaries of state, the chief election administrators in most states, should be subject to ethics rules. States should reshape their election certification processes to prevent partisan officials from rejecting legitimate vote totals.

This scratches the surface. Mr. Biden and Congress should impanel a high-level commission to examine these and other voting issues, including electoral college reform, in depth, and Congress and state lawmakers should prepare to legislate. Otherwise, the next time the country faces a tense election, the outcome could be far worse.

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