Credit Donald Trump with this much: When he finds a riff, he sticks with it.

For the better part of four years now, despite an utter paucity of evidence, the nation’s 45th president has claimed that our electoral system is so rife with voter fraud results cannot be trusted.

The opening salvo came in 2016 when Trump claimed that between 3 million and 5 million votes were illegally cast.

The former number, by the way, represents Hillary Clinton’s victorious margin in the popular vote. But we’re sure that was sheer coincidence. In 2018, a specially convened presidential commission found no evidence of any wrongdoing, an outcome that proved more speed bump than unscalable barrier to future fraud claims.

“Absentee Ballots are fine. A person has to go through a process to get and use them,” Trump thundered in a June 28 Tweet. “Mail-In Voting, on the other hand, will lead to the most corrupt Election is USA history. Bad things happen with Mail-Ins.”

Trump’s claims about mail-in balloting are “wrong and if used to prevent states from taking the steps needed to ensure public safety during November’s election, they will be deadly wrong. Mail ballot fraud is incredibly rare, and legitimate security concerns can be easily addressed,” the Brennan Center at New York University wrote in an April 10 analysis.

Now that effort, once merely offensive and dangerous, has been weaponized.

On Monday, Trump’s re-election campaign, joined by four Republican congressmen from Pennsylvania, sued the state’s Secretary of State’s Office and the election boards in all 67 counties, seeking to change the way mail-in ballots are sent and counted. 

The lawsuit alleges the current system jeopardized election security by, for example, setting up in-person ballot drop off boxes. Never mind the fact that counties run by Republicans and Democrats alike had utilized such boxes.

To be sure, the state has plenty of kinks to iron out before November. But based on anecdotal and first-hand reporting, while there were problems during Pennsylvania’s primary, there was hardly the chaos seen in Georgia or Wisconsin.

Voters rights advocates in Pennsylvania are already pushing back against the Trump camp’s claims, saying the lawsuit, is “an attempt to undermine the common-sense reforms that Pennsylvania’s elected officials, including Secretary of State Kathy Boockvar and all 67 county board of elections members, implemented to ensure that voters are able to exercise their constitutional right to vote without risking their health during the COVID-19 pandemic.”

The statement, by Scott Seeberg, state director of All Voting is Local, said the Pennsylvania action, along with a GOP-led attack on voter access in “Wisconsin in April are an all-out assault on the rights of voters to safely exercise their rights in the general election. Limiting voters’ access to vote by mail is no way to run a democracy. Pennsylvania’s elected officials are responsible for ensuring that the residents of the Commonwealth are able to vote safely at all times. This is nonnegotiable.”

It’s also proven immensely popular. As the Capital-Star’s Cassie Miller reported last week, mail-in ballots were more popular than in-person voting in more than a third of Pennsylvania counties, including such Democratic strongholds as Allegheny, Bucks, and Montgomery counties, as well as Philadelphia.

Delegitimizing mail-in balloting is the first step toward driving down turnout in a critical battleground state.

And if Trump should lose the Keystone State on Election Night, and that’s currently a real possibility, the campaign will seize on mail-in balloting as a way to discredit the state-level results, and with it, the general election results overall.

The campaign needs to be careful what it wishes for. Along with the Philly suburbs, mail-in balloting was also hugely popular in Pennsylvania counties Trump carried in 2016, including Luzerne County, which birthed a whole cottage industry of “Where it Went Wrong for Democrats” books.

If Trump succeeds in short-circuiting mail-in balloting in Pennsylvania, he may also prompt his own supporters to stay home, winning a battle, but ultimately losing the war.

An award-winning political journalist, John L. Micek is Editor-in-Chief of The Pennsylvania Capital-Star in Harrisburg, Pa. Email him at jmicek@penncapital-star.com and follow him on Twitter @ByJohnLMicek.