Senator Mark Warner was referring to a Washington Post article late Thursday saying that Trump was consulting with advisers "about his power to pardon aides, family members and even himself" in connection to the probe led by special counsel and former FBI director Robert Mueller.
Trump's lawyers were attempting to "corral the probe" and were compiling a list of Mueller's alleged potential conflicts of interest in order to "stymie his work," according to the Post, which quoted anonymous sources for the article.
In a statement, Warner said that Russia's interference in the 2016 elections "was an attack on our democracy. Both the Senate Intelligence Committee and Special Counsel Mueller are currently investigating whether any coordination occurred between Russia and individuals associated with the Trump campaign."
"The possibility that the President is considering pardons at this early stage in these ongoing investigations is extremely disturbing," said Warner, the senior senator from Virginia and vice-chair of the Select Committee on Intelligence.
"Pardoning any individuals who may have been involved would be crossing a fundamental line."
The White House has yet to comment on the Post report.
However in an interview with the New York Times on Wednesday, Trump warned Mueller that some of his family finances should be off-limits to the ex-FBI director's wide-ranging investigation.
Asked if Mueller looking at finances unrelated to Russia would be a red line, Trump responded, "I would say yes."
US intelligence agencies have accused Russian President Vladimir Putin of approving an influence campaign to sway the November 2016 vote in Trump's favor, allegations rejected by the Kremlin.
The Trump administration is currently under investigation by both Congress and the FBI over his presidential campaign's possible ties to Russia.
The controversy grew after Trump's eldest son Donald Jr released emails in mid-July showing he held a meeting during the campaign with Kremlin-connected figures, hoping to get dirt on his father's election rival, Democrat Hillary Clinton.
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