His administration is stocked with people who have questioned the legitimacy of elections, including some who have claimed that the 2020 presidential race was stolen.

By Alan Feuer, Nick Corasaniti and Alexandra Berzon Graphics by Ashley Cai

When President Trump sought to overturn his loss in the 2020 election and remain in power, resistance from within his own government helped to stop him.

Top Justice Department officials rejected his specious claims that the vote had been marred by widespread fraud. Senior officials at the Department of Homeland Security refused to go along with his outlandish efforts to seize voting machines. Cybersecurity experts praised the count as secure, and the intelligence community sidestepped his requests to declare that foreign nations had interfered in the results.

But Mr. Trump’s second term looks very different. The president has filled his administration with people who are sympathetic to his baseless claims that the presidential race more than five years ago was stolen.

These officials have been put into positions across the federal government, at the White House and in agencies where they could play a role in undermining the midterm elections and the 2028 presidential cycle.

At the same time, Mr. Trump has maintained allies in Congress and in state governments who could wield significant power over the process of counting votes and the seating of members of the House.

Abigail Jackson, a White House spokeswoman, sidestepped questions about Mr. Trump’s personnel decisions and instead asserted that he was “committed to ensuring that Americans have full confidence in the administration of elections.” She pointed to the president’s efforts to have Congress pass legislation that would require proof of citizenship to register to vote and photo identification to vote, prohibit mail-in ballots and bar the practice of ballot harvesting — having one person turn in mail ballots for several others.

“The vast majority of Americans support President Trump’s common-sense election integrity agenda,” Ms. Jackson said.

Officials from the Department of Homeland Security and the Office of the Director of National Intelligence said that the agencies were focused on keeping elections safe and secure, and were working to carry out the president’s policies on elections. The Justice Department did not respond to a request for comment.