Several agencies are examining what would happen if hackers turned off the power in contested districts, throwing polling places into the darkness, and with that, the integrity of the vote.

“It wouldn’t have to be a long outage” to create the perception that some votes might never be counted, said one official involved in the examination. At the National Security Agency, where a new Cybersecurity Directorate is about to be formed to coordinate defensive and offensive actions, there are new worries that Russian hackers are learning to operate from networks based in the United States — where they know the agency cannot legally investigate.

Less than 16 months from the next Election Day, the picture of American preparedness is mixed. The report issued Thursday by the Senate Intelligence Committee found that “some states were highly focused on building a culture of cybersecurity; others were severely underresourced and relying on part-time help.”

Federal officials say they are particularly worried about states like New Jersey, where only three counties are making the first experiments that create a paper trail for balloting. Pennsylvania and Texas also remain major concerns, the officials said.

And despite a flurry of activity across the federal government, coordination is a major challenge — chiefly because President Trump, who has only episodically acknowledged the Russian interference in 2016, reacts badly whenever aides bring up the topic, which he interprets as questioning the legitimacy of his election.

He has never overseen detailed meetings about hardening the American system, and he undermined a White House briefing for reporters about actions it was taking when he joked with President Vladimir V. Putin of Russia, mockingly warning him not to interfere in elections again. Because the administration eliminated the post of White House cybersecurity coordinator last year, interagency meetings on the issue are often held elsewhere, or are convened by House and Senate oversight committees.

Figuring out where to start is not hard. There are a flurry of studies and reports, including the National Academies of Sciences, Engineering and Medicine, Harvard’s “Defending Digital Democracy” program that trains campaign workers and state officials, and a new Microsoft program, Election Guard, that the company is providing free to states and election-machine manufacturers so that voters can track their ballots from casting to counting.