Donald Trump has cut Hillary Clinton's lead in half with just days to go before the first presidential debate, according to a new national poll.

Clinton is just 7 points ahead of Trump in a head-to-head matchup among likely voters, 48-41 percent, according to a new McClatchy-Marist poll released early Friday. Eight percent of respondents said neither candidate and 2 percent said they were undecided.

This is a stark change since early August in the same poll, when Clinton had a 15-point advantage (48-33) among registered voters nationwide. In that poll, 12 percent said they would not support either candidate and 5 percent said they were undecided.

In a four-way race, Clinton leads Trump by 6 points, 45-39 percent. Libertarian nominee Gary Johnson gets 10 percent and Green Party's Jill Stein has 4 percent.

Those surveyed preferred Clinton to handle issues of immigration by a 51-41 percent margin, trade by a 52-42 percent margin and terrorism by a 52-41 percent margin.

Respondents were also more inclined to say Clinton (57 percent) has the experience to serve in the White House, compared to the Republican nominee (30 percent). When asked who has the better temperament, likely voters picked the former secretary of state over Trump by a 50-38 spread.

The telephone-based poll of 1,298 adults nationwide was conducted Sept. 15-20. Of those 1,298 respondents, 758 were considered likely voters. The margin of error for all respondents was plus or minus 2.7 percentage points and the margin of error for likely voters was plus or minus 3.6 percentage points.