NEW YORK: Democrat Hillary Clinton has a 5 percentage point lead over Republican Donald Trump in the US presidential race, according to the latest Reuters/Ipsos opinion poll released on Friday, roughly the same advantage she has held all month.

The survey result showed little movement following Monday night's presidential debate, the first of three debates before the Nov. 8 election.

The Sept. 23-29 national tracking poll showed that likely voters support Clinton over Trump by 43 percent to 38 percent, while another 19 percent said they would not pick either candidate.

Clinton has mostly led Trump in the poll this year, and her level of support has been 4-5 percentage points higher than Trump's in each of the last four weeks.

In a separate poll that included alternative party candidates, Clinton led the field by 4 percentage points. Among likely voters, 42 percent supported Clinton, 38 percent supported Trump, 7 percent supported Libertarian candidate Gary Johnson and 3 percent supported Jill Stein of the Green Party.

Monday's debate was the most watched presidential debate in US history, with an estimated 84 million people tuning in for the 90-minute exchange. Some 56 percent of Americans adults who watched the debate said Clinton won, according to a Reuters/Ipsos poll released on Wednesday.

Voters appeared to be warming up to both candidates in Friday's poll. Some 48 percent of likely voters said they had an overall favourable view of Clinton, compared with 45 percent in the previous week, while 46 percent said they had a favourable view of Trump, up from 44 percent the week before.

The Reuters/Ipsos poll is conducted online in English in all 50 states. The poll included 2,501 people who were considered likely voters due to their registration status, voting history and stated intention to vote in the election. It has a credibility interval, a measure of accuracy, of 2 percentage points.

National opinion polls have differed this year in how they measure support for Clinton and Trump. Some polls, like Reuters/Ipsos, try to include only likely voters, while others include all registered voters. The Reuters/Ipsos tracking poll also gathers responses every day and reports results twice a week, so it often detects trends in sentiment before most other polls.

An average of major opinion polls aggregated by RealClearPolitics showed Clinton ahead of Trump by 2.9 percentage points on Friday, or 47.3 points to 44.4, slightly lower than the previous margin of 3 points on Wednesday, but well up from 0.9 point on Sept. 19.