Former Homeland Security Secretary Kirstjen Nielsen Kirstjen Michele NielsenMore than million in DHS contracts awarded to firm of acting secretary's wife: report DHS IG won't investigate after watchdog said Wolf, Cuccinelli appointments violated law Appeals court sides with Trump over drawdown of immigrant protections MORE was warned not to brief President Trump Donald John TrumpBiden on Trump's refusal to commit to peaceful transfer of power: 'What country are we in?' Romney: 'Unthinkable and unacceptable' to not commit to peaceful transition of power Two Louisville police officers shot amid Breonna Taylor grand jury protests MORE on possible Russian interference in the 2020 presidential election, according to The New York Times.

Acting White House chief of staff Mick Mulvaney Mick MulvaneyOn The Money: House panel pulls Powell into partisan battles | New York considers hiking taxes on the rich | Treasury: Trump's payroll tax deferral won't hurt Social Security Blockchain trade group names Mick Mulvaney to board Mick Mulvaney to start hedge fund MORE reportedly warned Nielsen not to bring the topic up in front of the president, despite Nielsen's concern that the Russians would attempt to influence another U.S. election.

Mulvaney reportedly said it “wasn’t a great subject and should be kept below [the president's] level."

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The reported warning came amid special counsel Robert Mueller Robert (Bob) MuellerCNN's Toobin warns McCabe is in 'perilous condition' with emboldened Trump CNN anchor rips Trump over Stone while evoking Clinton-Lynch tarmac meeting The Hill's 12:30 Report: New Hampshire fallout MORE's nearly two-year investigation of Russian interference in the 2016 presidential election, including whether Trump or his associates cooperated in the effort.

Trump has raged over Mueller's probe, regularly calling it a "witch hunt" and "presidential harassment." The investigation concluded in March, finding no criminal conspiracy between the Trump campaign and Russia.

Despite statements Trump has made that appear to cast doubt on whether Russians sought to influence the vote in 2016, his administration says he accepts that attempts were made.

Nielsen, who left the administration earlier this month, reportedly wanted to organize a Cabinet meeting to discuss strategy for preventing additional attempts in 2020. Three senior Trump administration officials and one former senior administration official described to the Times her frustration at the lack of progress on what she believed was an important national security issue.

Eight U.S. intelligence agencies concluded in January 2017 that Russians interfered in the 2016 election. The heads of multiple agencies have warned of ongoing attempts to infiltrate U.S. elections, although the director of national intelligence did not find any direct interference in the 2018 midterm elections.

Updated at 8:35 a.m.