The FBI has been accused of having a "double standard" in releasing potentially damaging material about Hillary Clinton while sitting on "explosive information" about Donald Trump.
US Senate Democratic leader Harry Reid wrote to FBI director James Comey about his decision on Friday to publicise the agency's discovery of new emails related to Hillary Clinton's private server.
"The double standard established by your actions is clear," he wrote in the letter.
"In my communications with you and other top officials in the national security community, it has become clear that you possess explosive information about close ties and co-ordination between Donald Trump, his top advisers, and the Russian government - a foreign interest openly hostile to the United States, which Trump praises at every opportunity.
"There is no danger to American interests from releasing it. And yet, you continue to resist calls to inform the public of this critical information."The public has a right to know this information. I wrote to you months ago calling for this information to be released to the public.
"By contrast, as soon as you came into possession of the slightest innuendo related to Secretary Clinton, you rushed to publicise it in the most negative light possible."
Clinton has been feeling the heat after Comey wrote to members of Congress to inform them the FBI had discovered new emails during an unrelated investigation.
The FBI is investigating whether there is classified information in the new emails, which were uncovered during the sexting investigation of Anthony Weiner, who is the estranged husband of Clinton aide Huma Abedin.
Reid said he believed Comey's actions in recent months demonstrated a disturbing double standard for the treatment of sensitive information, "what appears to be a clear intent to aid one political part over another".
He said Comey's actions may violate the Hatch Act, which bars FBI officials from using their official authority to influence an election.
"Through your partisan actions, you may have broken the law."
Comey's disclosure of the email discovery in a letter to Congress on Friday has thrown a spanner into the final days of the race between Clinton and Republican Donald Trump.
The Democratic candidate had opened a recent lead over Trump in national polls, but it had been narrowing even before the email controversy resurfaced.
The unexpected turn in the email controversy shook the financial markets' conviction of a Clinton victory in the election and the US dollar slipped against major currencies in early Asian trading on Monday.
FBI investigators have secured a warrant to examine the newly discovered emails to see if they are relevant to its probe of the private server used for government work by Clinton while she was secretary of state from 2009 to 2013.
Comey came under heavy pressure from Democrats on Sunday to quickly provide details of the emails, as Clinton allies worried the prolonged controversy could extend beyond the November 8 election and cast a shadow over a Clinton transition if she wins the White House.
FBI Director James Comey has come under fire for reopening an investigation into US Democratic presidential nominee Hillary Clinton’s emails, with Senate Minority Leader Harry Reid accusing him of breaching federal law.
The federal authorities are set to examine roughly 650,000 emails recovered from a laptop belonging to Anthony Weiner, a former US congressman who was married to Clinton’s top aide, Huma Abedin, until their divorce in late August.
Senator Harry Reid of Nevada wrote a letter to Comey on Sunday, saying that the FBI chief’s decision would favor the Republican Party and may change the outcome of the November 8 election, which is against the law.
“Your actions in recent months have demonstrated a disturbing double standard for the treatment of sensitive information, with what appears to be a clear intent to aid one political party over another,” the letter read.
“I am writing to inform you that my office has determined that these actions may violate the Hatch Act,” Reid continued.
According to the Hatchet Act, government officials are not allowed to use their influence to change the result of an election.
Comey announced his decision in a letter to Congress on Friday, only 11 days before the critical vote.
This is while Clinton had already undergone a thorough investigation for her use of a private server to exchange thousands of emails when she was secretary of state. She was cleared of all charges in July.
Reid told Comey that he regretted standing up for the bureau chief when “Republicans filibustered your nomination and delayed your confirmation longer than any previous nominee to your position.”
The attacks on Comey continued on Sunday night, when Clinton’s campaign released a letter signed by nearly 100 former prosecutors and Department of Justice officials.
“Many of us have worked with Director Comey; all of us respect him. But his unprecedented decision to publicly comment on evidence in what may be an ongoing inquiry just eleven days before a presidential election leaves us both astonished and perplexed,” the letter read.
Clinton’s support among voters took a nosedive following the news, allowing Republican nominee Donald Trump to reduce a 12-point gap with her to one point, according to the newest ABC News/Washington Post tracking poll, released Sunday.