Democratic presidential nominee Hillary Clinton's lead over Republican rival Donald Trump increased to more than 7 percentage points in the latest Reuters/Ipsos poll released on Tuesday.
A previous Reuters/Ipsos poll released last Thursday found Clinton with a lead of 3 points.
About 42 percent of likely voters favored Clinton and about 35 percent preferred Trump, according to the August 4-8 online poll of 1,152 likely voters, which had a credibility interval of plus or minus 3 percentage points.
The others would either pick another candidate, would not vote, or "don't know/refused", according to Reuters.
The results reflected a decline in support for Trump, rather than a boost for Clinton, noted Reuters. In last Thursday's poll, 42 percent of likely voters favored Clinton and about 39 percent favored Trump.
Among registered voters over the same period, Clinton held a lead of nearly 13 percentage points, up from about 5 percentage points on Thursday, according to the poll.
While Clinton has maintained a lead over Trump this past week, the size of the lead has been different ranging from anywhere between 7% in a CBS poll to as high as 9% in CNN/ORC's poll.
The five-day survey concluded on a mixed day for the Trump campaign. After squabbles last week with party leaders and the parents of a Muslim American soldier killed in Iraq, Trump sought to turn the page with a speech outlining an economic platform of tax breaks and regulatory rollbacks.
But in what was surely unwelcome news for Trump's campaign, 50 heavyweight Republican national security officials, in a letter published on Monday, said that Trump would be "the most reckless president in American history."
Trump hit back, saying the signatories "deserve the blame for making the world such a dangerous place", according to Reuters.
Trump faced more dissent within his party on Monday. A former CIA officer, Evan McMullin, announced he would run as an independent alternative to Trump for conservative Republicans, and Republican Senator Susan Collins said she would not vote for Trump.