U.S. Republican presidential nominee Donald Trump speaks to the Veterans of Foreign Wars conference at a campaign event in Charlotte, North Carolina, U.S. July 26, 2016.
Trump's gains came as he accepted his party's nomination to the Nov. 8 ballot at the four-day Republican National Convention in Cleveland last week, and as Clinton's nomination in Philadelphia this week was marred by party divisions and the resignation of a top party official.
The July 22-26 poll found that 39 percent of likely voters supported Trump, 37 percent supported Clinton and 24 percent would vote for neither. The poll had a credibility interval of 4 percentage points, meaning that the two candidates should be considered about even in support.
Clinton held a three-point lead on Friday, which was also within the credibility interval.
Clinton has solidly led Trump in the poll throughout most of the 2016 presidential race. The only times that Trump has matched her level of support were when the Republican Party appeared to be roughly aligned with his campaign.
In early May, Trump briefly pulled even with Clinton after his remaining rivals for the party nomination dropped out of the running. He held a 0.3 percentage point lead over Clinton on May 9, the last time he was nominally ahead.
Trump fell back in the poll as he feuded with party bosses over comments he made about Hispanics, Muslims and immigrants, but he rebounded this month as his candidacy took the national spotlight at the Cleveland convention.
The Democratic party is hoping for a similar boost during its convention this week in Philadelphia, but the confab had a rough start: the Wikileaks website released emails on Friday that enraged many voters who had supported Clinton's rival for the nomination, Senator Bernie Sanders of Vermont, showing that party officials had looked for ways to undermine his candidacy.
The chair of the Democratic National Committee, Debbie Wasserman Schultz, announced her resignation afterward.
On Monday, some speakers at the Democratic convention were booed by Sanders supporters, and hundreds of protesters took to the streets to protest Clinton's candidacy.
Presidential candidates usually get a boost in popularity following their party conventions.
In 2012, Republican nominee Mitt Romney jumped by 5 percentage points to pull about even with President Barack Obama after the Republican convention. After the Democrats held their convention, Obama then rose by a few percentage points and again pulled ahead.
The Reuters/Ipsos poll was conducted online in English with about 962 likely voters.
(Editing by Richard Valdmanis and Leslie Adler)