Washington: The Senate Intelligence Committee concluded Thursday that election systems in all 50 states were targeted by Russia in 2016, an effort more far-reaching than previously acknowledged and one largely undetected by the states and federal officials at the time.

But while the bipartisan report’s warning that the United States remains vulnerable in the next election is clear, its findings were so heavily redacted at the insistence of US intelligence agencies that even some key recommendations for 2020 were blacked out.

The report — the first volume of several to be released from the committee’s investigation into Russia’s 2016 election interference — came 24 hours after the former special counsel, Robert Mueller, warned that Russia was moving again to interfere “as we sit here.”

While details of many of the hackings directed by Russian intelligence, particularly in Illinois and Arizona, are well known, the committee described “an unprecedented level of activity against state election infrastructure” intended largely to search for vulnerabilities in the security of the election systems.

It concluded that while there was no evidence that any votes were changed in actual voting machines, “Russian cyberactors were in a position to delete or change voter data” in the Illinois voter database. The committee found no evidence that they did so.

In his testimony to two House committees Wednesday, Mueller had sought to highlight the continued threat that Russia or other adversaries would seek to interfere in the 2020 election. He said many more “countries are developing capability to replicate what the Russians have done.”

While the Senate Intelligence Committee’s findings were bipartisan, they came on a day when Sen. Mitch McConnell of Kentucky, the Republican majority leader, moved again to block consideration of election security legislation put forward by Democrats.

McConnell has long opposed giving the federal government a greater hand in an institution of American democracy typically run by the states.

And despite the warnings about the Russia threat, he argues that Congress has already done enough — passing $380 million worth of grants for states to update their election systems and supporting executive branch agencies as they make their own changes.

The Democratic proposal, already passed by the House, would have given the states hundreds of millions of dollars in grants, mandated the use of backup paper ballots and required risk-limiting postelection audits.

“This is not a Democratic issue, a Republican issue,” said Sen. Chuck Schumer of New York, the Democratic leader. “This is not a liberal issue, a moderate issue, a conservative issue. This is an issue of patriotism, of national security, of protecting the very integrity of American democracy, something so many of our forebears died for.”

“And what do we hear from the Republican side?” he said. “Nothing.”