For years, Republicans have pushed to improve election integrity. Democrats, aided by the courts, have fiercely resisted efforts to ensure honest elections. But there’s no good argument against making sure that everyone who casts a ballot is eligible to do so, and that they cast only one per election.

After all, illegal voting is not a victimless crime. Every invalid ballot dilutes the votes of the rest of us. A democracy that does not secure the polls represents rule by the crooked rather than by the people.

Nevertheless, Democratic politicians have fought to make fraud simple. They don’t put it that way, waxing eloquent about battling against voter “suppression” and the like. But the only person who suffers when an ID is required is someone seeking to cast a ballot in another person’s name.

President Donald Trump caused a liberal brouhaha when he asserted that he would have won the popular vote if illegal votes had not been cast. There’s no way to prove his claim, but it doesn’t really matter. Old Dominion University’s Jesse Richman figures that Hillary Clinton gained about 834,000 votes from noncitizens alone who cast ballots.

By his estimate, 6.4 percent of the 20 million adult foreigners living in America voted, most of them for the Democratic nominee. This certainly inflated her popular vote total and might have added electoral votes. Had Trump done slightly worse in the battleground states, the illegal votes could have given her victory in Michigan, Pennsylvania, and Wisconsin, and thus the presidency.

Apart from noncitizens voting illegally, there’s plenty of fraud committed by people voting for the dead or in multiple jurisdictions. Back in 2012, the Pew Center on the States found nearly 24 million inaccurate or invalid registrations -- one of every eight. There were almost two million dead people on the rolls and three million registered in multiple states. About 70,000 people were registered in at least three states!

That’s a lot of potential erroneous or fraudulent votes. Some problems are impossible to miss: an investigation by the American Civil Rights Union (ACRU) found numerous registrants on the Pennsylvania rolls who were apparently hale, hearty, and civically active at age 100 or even 200 years.  In 2013, the New York City Department of Investigation sent out staffers to cast evidently fraudulent ballots. In an incredible 97 percent of the cases the investigators were allowed to vote. When confronted with the results, the Board of Elections suggested charging the inspectors with election fraud!

Orchestrating vote fraud takes effort. But voting by noncitizens is easy if they’re not required to prove citizenship when registering or a photo ID when voting. And most of them lean Democratic. Acting individually, one by one, without any organized conspiracy, they can change election results for the presidency and other offices across America.

There’s no need to debate the impact of fraud on the last election. No one will ever know precisely how many votes Donald Trump was cheated out of. Thankfully, it didn’t change the presidential outcome. However, Republicans might have lost some members of Congress and state legislators.

Instead, our focus should be on cleaning up the voter pool to prevent mistakes and fraud next time. The ACRU has been using the federal courts to force voter roll cleanup for the last three years and is currently engaged in a battle royal with election officials in Broward County, Florida.

Data from the U.S. Election Assistance Commission and the Census Bureau show that voter rolls are contaminated across America, in many cases with more registrants than residents -- at least living. That’s an open invitation to fraud, and utterly indefensible.

As Pew found, noncitizens also fill the rolls. In many cases that might reflect more enthusiasm about living in America than ill intent. But it’s still wrong. People should become citizens and then vote.

Also serious is the problem of people being registered in more than one state. It’s easy for someone to move and end up on a second voter roll. One case isn’t a big deal. But millions of them help create error-filled voter lists. Which opens the way for dishonest election results.

In addressing congressional Republicans President Donald Trump recently said, “We also need to keep the ballot box safe from illegal voting.” How can any American disagree with that? “We are going to defend the votes of the American citizen,” he added. Shouldn’t every elected official want to do the same?

The fact that Democrats do not is telling. If they believe proposals from Republicans would be ineffective or overbroad, they should propose better alternatives. Instead, they routinely follow a scorched earth policy against even the most mundane remedy, such as requiring a photo ID to vote. The only reason to do so is to protect illicit voting, which they expect to run in their favor.

Election integrity cannot be delayed. The closer it gets to the next election, the more the Democrats will turn it into a political football. American democracy depends upon accurate voter rolls and honest voting. We must safeguard Americans’ democratic birthright.

J. Kenneth Blackwell, a former mayor of Cincinnati and Ohio Secretary of State, is a Policy Board member and Senior Fellow for the American Civil Rights Union.