Hillary Clinton FBI investigation: 5 things to know

1. Officials reportedly discovered 650,000 emails on a laptop computer used by former New York Rep. Anthony Weiner and top Clinton adviser Huma Abedin, his estranged wife. Citing sources familiar with the investigation, The Wall Street Journal reported Sunday that thousands of the emails, which were discovered during an investigation into allegations that Weiner sent illicit messages to 15-year-old girl, "could have been sent to or from the private server that Mrs. Clinton used while she was secretary of state." Although theJournal reported that examining the emails could take weeks, USA Today said officials "have not completely ruled out the possibility of completing the review by Election Day." Read more here.

>> FBI investigates newly discovered emails for possible ties to Hillary Clinton

2. Abedin has said she doesn't know how her emails wound up on the laptop, according to The Washington PostAbedin "was not a regular user of the computer," which she "viewed as her husband's," the Post reported, citing a person who spoke on condition of anonymity. Read more here.

>> Read the letter by FBI informing Congress Hillary Clinton email investigation back open

3. Senate Democratic Leader Harry Reid says Comey may have broken the law. In a letter to the FBI director Sunday, Reid wrote: "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."

Comey was a longtime Republican but is "not registered any longer," he said in July.

"Harry Reid is a disgrace to American politics, among worst men ever in Senate," tweeted Arkansas Sen. Tom Cotton. "He can't go soon enough, & many Democrats privately agree."

>> A look at Hillary Clinton's 2016 presidential campaign controversies

4. How will the news affect the polls? Although it will take a few days to see poll results that factor in likely voters' reaction to the Comey letter, the latest ABC News/Washington Post tracking poll was conducted partly after the news broke. That poll puts Clinton narrowly ahead with support from 46 percent of likely voters, compared with 45 percent for Trump. Read more here.

Meanwhile, a YouGov/CBS News poll found that 71 percent said the FBI news "either won't change their thinking, or in some cases, they've already voted." Read more here or here.

5. How are the candidates responding? Republican presidential nominee Donald Trump has been blasting Clinton hard since the news broke, speculating that she is guilty of "willful and deliberate criminal conduct" at a campaign stop Sunday in Colorado.

"I would think they have some real bad ones, but we're gonna find out. ... Maybe not," he said, according to The Washington Post.

Speaking at a campaign event in Florida, Clinton avoided talking about the probe.

"I want you to know I am focused on one thing: you, the problems that keep you up at night," she said. "There's a lot of noise and distraction, but it really comes down to what kind of future we want."

Both campaigns have urged the FBI to provide more information about what they have found in their review.