For the first time, Michelle Obama joined Hillary Clinton on the campaign trail in Winston-Salem, N.C. The two women electrified supporters at the rally, giving a new injection of energy into the campaign with nearly one week left before the election. (Alice Li/The Washington Post)

Donald Trump has gained on Hillary Clinton during the past week, according to a new Washington Post-ABC News tracking poll, solidifying support among core Republican groups as well as political independents.

Roughly 6 in 10 still expect Clinton to prevail, while the poll finds shrinking concerns about the accuracy of the vote count and voter fraud in the election.

[Read full poll results here]

Clinton holds a slight 48-44 percent edge over Trump among likely voters, with Libertarian Gary Johnson at 4 percent and Green Party nominee Jill Stein at 1 percent in the survey completed Sunday through Wednesday. Clinton held a six-point edge in the previous wave and a 12-point edge in the first wave of the tracking poll by ABC News Sunday (50 percent Clinton vs. 38 percent Trump). In a two-candidate contest, Clinton holds a five-point edge over Trump, 50 to 45 percent.

Trump’s growth in support from 38 percent to 44 percent is fueled by shored-up support among Republican-leaning voting groups as well as a significant boost among political independents. Trump has made up ground among whites, particularly those without college degrees and women. Trump now leads by a 30 percentage point margin among white voters without college degrees, up from 20 points from this weekend. White women now tilt toward Trump by 48 to 43 percent after leaning 49 to 43 percent in Clinton’s favor before.

Trump saw his biggest gains among political independents, favoring Trump by a 12-point margin in the latest tracking poll, 49 to 37 percent, after giving Clinton a narrow edge in late last week. Neither candidate has maintained a consistent lead among independent likely voters in Post-ABC polling this fall.

[See Clinton and Trump support among key voting groups]

Other surveys this week paint a mixed picture about how much the race has shifted. The Huffington Post’s national average of polls finds Clinton with a seven-point advantage over Trump, hardly changed in recent weeks. FiveThirtyEight’s forecast, which takes into account state-level surveys, finds only a slight dip in Clinton’s expected popular vote based on recent surveys.

Most expect Clinton to prevail

The Post-ABC tracking poll finds nearly twice as many voters expect Clinton to win the election as predict Trump will prevail (59 percent vs. 30 percent), results that are similar to early September. What has changed is a growing share who think Clinton will win “easily,” rising from 19 percent to 27 percent.

Majorities of Clinton and Trump supporters expect their candidate will win, but there’s a clear gap in certainty. Fully 93 percent of Clinton supporters think she will prevail, and 45 percent expect an easy victory. Among Trump backers, 67 percent expect him to win, but only 20 percent think his victory will come easy.

At a rally Thursday with Michelle Obama, Clinton warned her supporters against complacency and urged them to vote early, saying the race is likely to be closer than polls suggest.

Voter fraud and accuracy of the vote count 

Sizable minorities of likely voters express concerns about fraud and inaccuracy at the ballot box, though worries about both have declined in the past month. Fewer than four in 10 voters now say voter fraud occurs very or somewhat often (37 percent), down from 47 percent in early September. Studies of voter fraud have found that it is very rare.

In a separate question, the share of voters saying they do not have confidence votes will be counted accurately dipped from 33 to 28 percent, while the percentage saying they are "very confident" rose from 31 to 43 percent.

Seven in 10 Trump supporters say voter fraud occurs at least somewhat often, including 34 percent who think it happens “very often.” And Trump voters are split on whether votes will be counted accurately across the country, with 50 percent at least somewhat confident and 49 percent “not too” or “not at all” confident.

While Trump voters’ concerns about fraud and vote counting have not changed significantly since last month, Clinton supporters expressed growing confidence in the election process. The share of Democrats who are “very confident” the vote will be accurately counted has grown from 45 percent last month to 70 percent in the new Post-ABC poll. And while more than 1 in 5 Democrats last month thought voter fraud occurs at least somewhat often, that has fallen to slightly more than 1 in 10 in this week’s poll.

This Washington Post-ABC News poll was conducted by telephone October 23-26, 2016, among a random national sample of 1,775 adults, including landline and cell phone respondents. Overall results have a margin of sampling error of plus or minus 2.5 points; the margin of sampling error is plus or minus three percentage points among the sample of 1,150 likely voters. Sampling, data collection and tabulation by Abt-SRBI of New York.