Hillary Clinton and Donald Trump are separated by only two percentage points in a new Washington Post-ABC News tracking poll, ending a week in which the race has tightened as core Republican groups have returned to Trump’s fold.

Likely voters split 47 percent for Clinton and 45 percent for Trump, according to the survey conducted Monday through Thursday. That's little changed from a 48-44 split in the previous day's tracking results, which covered Sunday through Wednesday, but it is a substantial tightening since last weekend when Clinton led by a wide margin.

The up-and-down campaign received another jolt with Friday's news that the FBI is looking into additional Clinton emails from her time as secretary of state, an issue about which the public has been especially critical of Clinton. A September Washington Post-ABC News poll found 62 percent the public overall disapproving of her handling of questions about email while secretary of state, including 48 percent who disapproved strongly.

The Fix's Aaron Blake breaks down reactions to the FBI's announcement and explains why it matters to Hillary Clinton's presidential campaign. (Sarah Parnass/The Washington Post)

A clear 59 percent majority continues to expect Clinton to win on Nov. 8, including more than 9 in 10 Clinton supporters, although the survey finds few signs that overconfidence is dampening enthusiasm. Among likely voters, only 2 percent who support Clinton and expect her to win say their prediction makes them less motivated to vote, including just 1 percent of those who think she will win "easily." A similarly small 2 percent of Trump supporters who anticipate he will win say their expectation makes them less likely to vote.

Clinton's campaign has expressed concerns about complacency this week as it pushes supporters to turn out even as polls showed her with a comfortable lead.

National polls released this week have shown ranging sizes of Clinton's advantage. Surveys by Fox News and Investor's Business Daily/TIPP each found Clinton up a narrow three percentage points among likely voters, while she led by nine points in separate CNBC and USA Today/Suffolk polls and by 14 points in an Associated Press-GfK poll. The varying results come as polls capture reactions to a slew of news events, including ranges of enthusiasm among each candidate's supporters and unity among Republicans who have wavered in support for Trump.

The survey finds little sign of a large engagement advantage among Democrats or Republicans at this point — 62 percent of registered voters in both groups say they are following the race "very closely," and 88 percent in each group say they are "absolutely certain to vote" or volunteer they have already cast their ballot.

Likely voters who support Trump are less confident that he will win than Clinton, with two-thirds (66 percent) predicting he will prevail while 22 percent think Clinton will win and the rest are uncertain. Yet nearly 7 in 10 Trump supporters say their expectations for the outcome make them motivated to turn out (69 percent), including a similar 77 percent of those who think he will win. Just over one-quarter of all Trump voters say expectations don't make a difference in their vote, while 2 percent say it makes them less likely to show up.

Hillary Clinton’s campaign comes to an end

MANHATTAN, NY - The morning after loosing to Republican Nominee Donald Trump in the general Presidential election, Democratic Nominee for President of the United States former Secretary of State Hillary Clinton, accompanied by former President Bill Clinton, Chelsea Clinton, Senator Tim Kaine and Anne Holton, speaks to supporters and campaign staff in a packed ballroom at The New Yorker Hotel in midtown Manhattan, New York on Wednesday November 9, 2016. (Melina Mara/The Washington Post)

Clinton supporters are slightly less apt to say their expected outcome makes them more motivated to vote, 61 percent, while 37 percent say it doesn't make a difference and 2 percent say they're less energized to vote as a result.

The presidential race has been prone to sharp swings following major campaign news, with less stability than during President Obama's reelection run in 2012. Trump's victory in the Republican primary boosted him to a narrow three-point edge over Clinton in May, his best of the year, but he lost ground in June after sharp criticism of a judge's Mexican heritage and his controversial response to the Orlando shootings.

Clinton's lead expanded after the party conventions in late August and negative reactions to Trump's dispute with a Gold Star family, but the race narrowed to a dead heat leading up to the first debate in late September, before Clinton's lead grew again after she was seen as winning that encounter. Last weekend, tracking results released by ABC News found Clinton with her largest lead of 12 points following a week in which Trump was seen as losing the third debate and mocking women who accused him of sexual assault.

The latest Post-ABC News tracking poll finds an electorate lining up in very similar ways to four years ago. Clinton holds a 51-to-41 lead among women while Trump leads by 49-to-42 among men, a similar split as between Obama and Mitt Romney in in 2012. Non-white likely voters overall favor Clinton by 51 percentage points, smaller than Obama's 61-point edge, while whites tilt toward Trump by a 16-point margin (just shy of Romney's 20-point lead).

Trump leads by a wide, 82-12 percent margin among white evangelical protestants, slightly wider than Romney's 78-21 advantage in 2012. Clinton dominates among voters with no religious affiliation, leading by more than 3 to 1 (66 to 18 percent), a similar edge as Obama in 2012 (70-26).

What Donald Trump is doing on the campaign trail

MANCHESTER, NH - NOVEMBER 7: Republican presidential candidate Donald Trump speaks during a campaign event at SNHU Arena in Manchester, NH on Monday November 07, 2016. (Jabin Botsford/The Washington Post)

The one clear shift from 2012 is a sharp educational split among whites that has been tracked all year. Whites with college degrees favor Clinton by double digits (53-41), while non-college-educated whites favor Trump by more than 30 points (62 to 28). The split was far smaller in 2012, when Romney won both groups: white college grads by 14 points and non-college grads by 25.

This Washington Post-ABC News poll was conducted by telephone Oct. 24-27, among a random national sample of 1,779 adults including landline and cellphone respondents. Overall results have a margin-of-sampling error of plus or minus 2.5 points; the error margin is plus or minus three points among the sample of 1,148 likely voters. Sampling, data collection and tabulation by Abt-SRBI of New York.