Sharp decrease on Hillary Clinton lead on Donald Trump: Reuters/Ipsos Poll

This file photo taken on August 25, 2016 shows Democratic presidential candidate Hillary Clinton speaking at a campaign event in Reno, Nevada. (AFP photo)

US Democratic presidential nominee Hillary Clinton’s lead over her Republican rival Donald Trump has seen a sharp decrease, according to a new poll.

According to the latest Reuters/Ipsos daily tracking poll released on Friday, Clinton is 5-percentage-point ahead of Trump in terms of national support, 41 percent to 36 percent.

This marks a 7-point drop from the poll’s Tuesday edition, which showed Clinton held a 12-point edge over the real estate mogul, 45 to 33.

In the new poll, nearly 23 percent of the likely voters said they would pick neither candidate, answering "refused," "other" or "wouldn't vote."

Clinton’s declining support has, in large part, been attributed to a series of fierce attacks from the Trump campaign over the past few days.

The former secretary of state has been accused by Trump of doing political favors for some of the people who donated money to her family’s foundation when she was in office from 2009 to 2013.

Her use of a private server to exchange classified emails also made the headlines again this week, after a judge ordered her to provide written testimony under oath about why she used the server.

Last month, FBI Director James Comey declined to recommend prosecuting Clinton, despite evidence that indicated she was “extremely careless” in her handling of the emails.

The two candidates have also been locked up in a heated battle to win the support of African American families and other minorities.

The new poll also showed that Clinton’s lead over Trump dropped to three points when Libertarian candidate Gary Johnson and Green Party nominee Jill Stein were included.

According to the poll, some 39 percent of the likely voters supported Clinton, while 36 percent favored Trump, 7 percent chose Johnson and 3 percent backed Stein.

New endorsement for Clinton

On Friday, the International Brotherhood of Teamsters, which is America’s fourth-largest union, announced its support for Clinton.

The endorsement comes after the former first lady supported a decision by the Treasury Department earlier this year to cut pension benefits for the union’s retirees.

“We are proud to endorse Hillary Clinton for President of the United States,” Teamsters General President James P. Hoffa said in a statement. “She is the right candidate for the middle class and working men and women across the country.”