The Supreme Court on Monday blocked President Trump's executive order to restrict mail ballots, dealing him a major legal blow. However, Mr. Trump's effort to assert control over elections continues through alternative avenues. Just days before the court ruling, the Justice Department sent threatening letters to at least 30 top election officials nationwide, escalating a fight for access to private voter data and election records.

Federal agents are scouring state voter rolls for noncitizens despite a lack of evidence of widespread fraud. Mr. Trump's homeland security secretary recently pushed to investigate whether commonly used voting machines can be trusted, casting doubt on digital systems. "This is far from over," said Benjamin Hovland, ousted from the bipartisan Election Assistance Commission this year. He acknowledged the court decision mitigated real-world impact on voters but called Mr. Trump's actions alarming, stating they "undermine confidence in our democracy." Mr. Trump argues he is securing vote integrity, though his claims of widespread fraud have been repeatedly debunked. Critics say his actions needlessly sow doubt.

The White House did not immediately respond to comment requests. In his second term, Mr. Trump has surrounded himself with loyalists and installed election deniers in key posts, facing fewer internal government pushbacks than in 2020. Despite Monday's loss, Mr. Trump, who has said he wanted to "take over" and nationalize elections, faces mounting legal setbacks.

Before the Supreme Court decision, two lower court judges ruled his mail-in balloting changes were likely illegal close to the November elections. The Justice Department has sued 30 states for unredacted voter lists, losing 23 cases. Decisions remain pending in the rest.

These federal actions and court decisions have alarmed local election officials and voters. This month, chief election officials in seven Republican-controlled states filed a brief arguing it was too close to Election Day for major changes.