Washington (AFP) - Donald Trump and Hillary Clinton are in a dead heat as the Republicans head into their presidential nominating convention next week, a poll released Thursday said.

Each candidate landed support from 40 percent of registered voters in the New York Times/CBS News poll.

In the same poll last month, the Democrat Clinton had a six point lead over Trump -- 43 to 37 percent. Now that cushion is gone.

The latest figures come soon after the results of an FBI investigation into Clinton's use of a private email server while she was secretary of state, which revived the controversy amid an onslaught of criticism by Republicans.

Some 67 percent of voters say she is not honest and trustworthy, the poll found. That number represents a five percent increase from a CBS News poll last month.

Only 28 percent now see Clinton as honest, Thursday's poll showed.

Trump follows close behind, with 62 percent of respondents saying they do not trust him.

However, that number has remained constant since last month despite an onslaught of criticism from the Clinton campaign over his claims about his business record.

Many more voters said they believe Clinton is better prepared to be president -- 50 percent, compared to 30 percent for Trump. Still, that number represents a drop of nine percent since last month.

Clinton also lost ground on her overall image, with only 28 percent of voters saying they hold a positive view of her, compared with 33 percent last month. Trump's numbers improved slightly, with 30 percent saying they hold a positive view of him compared to 26 percent last month.

Thursday's poll showed an electorate deeply divided not only between Republicans and Democrats but also along gender and racial lines. Clinton has a strong lead among women, African Americans and younger voters. Trump leads among men and white voters.

With the killings of black men by white police officers and attacks on police last week roiling the country, however, 60 percent of voters said Clinton would be better at handling the issue of race relations.

The Democrats hold their convention later this month.