A bipartisan group of senators is expected to slam former President Barack Obama's administration for its response to Russian election interference in the 2016 presidential election.

The Senate Intelligence Committee, which is conducting an investigation into the government's response to Russian election meddling, has already criticized the Department of Homeland Security for its "inadequate" defense against the hacking effort.

In a May report, the committee said that Obama administration officials worried that warning the public about election interference could damage the public's faith in election integrity.

But an upcoming report, slated to be released by September, is expected to be more critical of Obama than the committee's past statements, according to a source familiar with the committee's work.

The report has not yet been finalized, and the committee is scheduled to hold an open hearing on the matter next week. A source close to the Republicans on the committee said they are expecting to hold a closed hearing on the matter, as well.

There had been indications the panel would formally criticize the Obama administration's response. The committee's vice chair, Sen. Mark Warner, D-Va., called the administration's handling of Russian election interference "flat-footed" during a June 20 hearing on Russian interference in U.S. elections.

"Our collective response was inadequate to meet Russia's escalation," Warner said, though he noted that he believed President Donald Trump also deserved blame because of his claims as a candidate that the election had been rigged.

Sen. Richard Burr, R-N.C., the committee's Republican chairman, said during the hearing that Obama officials appeared to be operating "without a playbook."

Reuters reported in May that investigators working for the Senate Intelligence Committee concluded that the Obama administration acted too slowly after they suspected Russian interference.

Eric Schultz, a senior Obama advisor, said the former president would wait until the report was public to issue a response.

"We’re not going to be in a position to respond to an anonymous, unconfirmed single-source leak of a report that’s not even finished," Schultz said.

Some Democrats are wary that criticism of Obama could distract from allegations that Trump had improper ties with Russians. Yet they are still expected to sign on to the report, which is expected to argue that Obama should have been more vocal and transparent with the public about what was happening.

The Senate Intelligence Committee has performed its work in a largely bipartisan fashion since it opened its investigation in early 2017, in contrast to the heavily politicized investigation undertaken by the House Intelligence Committee.

Michael Daniel, a top Obama cybersecurity official, told lawmakers in June that it was "highly likely" that Russians had scanned U.S. election systems in all 50 states. The intel panel has estimated that Russia targeted at least 18, and possibly 21, state election systems.

In a small number of states, the committee found, hackers affiliated with Russia were "in a position to" alter voter registration data, but not votes.

Congress approved nearly $400 million to improve federal election security in March. Forty-eight states and territories have already submitted requests for funding, U.S. Election Assistance Commissioner Thomas Hicks told lawmakers on Wednesday.