Hillary Clinton is leading Donald Trump in one new national poll and in two other polls measuring support in two key swing states.

An NBC News/SurveyMonkey Weekly Election Tracking poll released Tuesday found that Clinton leads Trump nationally by 9 percentage points -- 50 percent to 41 percent.

In a four-way race involving Libertarian Gary Johnson and Green Party candidate Jill Stein, Clinton leads Trump 43 percent to 37 percent. Eleven percent support Johnson and 4 percent back Stein, the poll found.

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The poll also found that more than 40 percent said Clinton has the personality and temperament to serve as president while only 17 percent said the same about Trump. Only 19 percent of Republican voters and those who lean that way said Trump has the personality to serve effectively.

Clinton is also performing well in the key battleground state of Florida, according to a Monmouth University survey released Tuesday, in which she leads Trump by 9 percentage points. She leads him 48 percent to 39 percent.

As for the state's senate race, GOP incumbent Sen. Marco Rubio leads his two Democratic challengers. He leads Democratic Rep. Patrick Murphy 48 percent to 43 percent and leads Rep. Alan Grayson 50 percent to 39 percent.

Meanwhile, in Virginia, Clinton continues to maintain a double-digit lead over Trump. A Washington Post poll released Tuesday found that she leads him there by 14 percentage points -- 52 percent to 38 percent among registered voters.

The NBC/SurveyMonkey poll surveyed 15,179 adults between August 8 and 14 with a 1.2 percentage point margin of error. The Monmouth survey polled 402 Florida residents between August 12 and 15 with a roughly 5 percentage point margin of error. The Washington Post poll surveyed 888 registered voters between Aug. 11 and 14 with a 4 percentage point margin of error.