It’s tempting to blame the lack of progress on President Trump, in whose mind the topic of election security has become tangled with questions about the legitimacy of his 2016 win. White House aides have learned to avoid this sore subject with the president, rendering his administration unwilling and unable to prioritize it. In some cases, members of Mr. Trump’s team have sought to derail reform legislation, and many Republican lawmakers are loath to venture into such unstable territory.

But causes of this stalemate stretch far beyond the president’s fragile ego. Mitch McConnell, the Senate majority leader, has long opposed federal involvement in election management. During the debate over the Help America Vote Act of 2002, a reform package sprung from the vote-counting failures of the 2000 presidential race, Mr. McConnell repeatedly spoke out against a one-size-fits-all approach in favor of leaving election matters up to the states.

Mr. McConnell also may be the Senate’s fiercest crusader against regulating the flow of campaign cash. It is thus unsurprising that he has not embraced proposals such as the bipartisan Honest Ads Act, which would require funding transparency for online political ads, nor the Disclose Act, a version of which has been introduced in every Congress since 2010, aimed at exposing the “dark money” flooding groups like labor unions, trade associations and super PACs.

Even absent a president who considers election security a personal affront, Mr. McConnell most likely would be stonewalling, accusing Democrats, as he did recently, of trying to “nationalize everything” and wanting “the federal government to take over broad swaths of the election process because they think that would somehow benefit them.” As things stand, he is happy to exploit tensions, spinning the calls for reform as an example of how the president “gets picked at every day” by Democrats. “They’re trying to keep the 2016 election alive,” he contended last month. “They just can’t let it go.”

He may have a point. Mr. McConnell is not the only lawmaker playing politics. Democrats have aggressively pushed multiple bills that would require campaigns to notify federal authorities of any offers of foreign assistance. This might be a useful tightening of election law, but it is also a rebuke of President Trump, whose campaign team failed to report overtures by the Russians in 2016 and who recently expressed an openness to future offers.