The presidential election results are settled. But the battle over new voting rules, especially for mail-in ballots, has just begun.

WASHINGTON — In Georgia, Arizona and other states won by President Biden, some leading Republicans stood up in November to make what, in any other year, would be an unremarkable statement: The race is over. And we lost, fair and square.

But that was then. Now, in statehouses nationwide, Republicans who echoed former President Donald J. Trump’s baseless claims of rampant fraud are proposing to make it harder to vote next time — ostensibly to convince the very voters who believed them that elections can be trusted again. And even some colleagues who defended the legitimacy of the November vote are joining them.