WASHINGTON (Reuters) - A bipartisan Senate report released on Thursday criticized the Obama administration for failing to react quickly or thoroughly enough to counter Russian interference in the 2016 U.S. presidential election

The administration “was not well postured” to combat the meddling and was constrained in responding by a heavily politicized environment in a volatile election year and other factors that inadvertently aided Moscow, according to the Senate Intelligence Committee’s report.

The findings are significant in that minority Democrats joined majority Republicans in criticizing the Obama administration’s handling of what the panel and U.S. intelligence agencies concluded was a Russian operation to sway the presidential vote to then-Republican candidate Donald Trump over his Democratic rival, Hillary Clinton.

Two Democrats - Ron Wyden and Martin Heinrich - took the unusual step of appending to the report separate statements charging that the report lacked critical information on the Obama administration’s decision to brief only eight senior congressional leaders on the Russian meddling.

“When the country is under threat, the government has a particular responsibility to provide all relevant intelligence to the full congressional intelligence committees,” Wyden wrote.

The report determined that high-level White House meetings on the Russian operation were “atypically” restricted to a small circle of senior aides, excluding other key officials and subject matter experts.

The decision to restrict information about the Russian operation was a major theme throughout the 49-page report, the third issued by the panel on its investigation into Moscow’s vote-meddling.

“The committee found that the decisions to limit and delay the information flow regarding the 2016 Russian active measures campaign, while understandable, inadvertently constrained the administration’s ability to respond,” the report said.

Russia has denied U.S. charges that it employed cyber hacking, disinformation, and other means to influence the election outcome in Trump’s favor.

A report by former Special Prosecutor Robert Mueller into the Russian operation released in April 2019 found insufficient evidence that the Trump campaign colluded with Moscow in the election interference.

In a key finding, the Senate report said that the Obama administration’s response to the Russian meddling was constrained by the heavily politicized environment in the United States and fears that public warnings would undermine confidence in the election outcome, “thereby inadvertently helping the Russian effort.”

It also found that the administration was not properly prepared to counter the Russian meddling with “a full range of readily available policy options,” and that the top White House national security advisors only learned of Russian hacking of the Democratic National Committee’s computers from news reports in June 2016.