Democratic presidential nominee Hillary Clinton Hillary Diane Rodham ClintonJoe Biden looks to expand election battleground into Trump country Biden leads Trump by 12 points among Catholic voters: poll The Hill's Campaign Report: Biden goes on offense MORE leads Republican Donald Trump Donald John TrumpBubba Wallace to be driver of Michael Jordan, Denny Hamlin NASCAR team Graham: GOP will confirm Trump's Supreme Court nominee before the election Southwest Airlines, unions call for six-month extension of government aid MORE by 5 points, according to an NBC News/SurveyMonkey weekly election tracking poll.

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Clinton is favored by 45 percent of likely voters and Trump is backed by 40 percent in a four-way matchup. Clinton's lead over the GOP nominee is unchanged from last week's poll.

Libertarian nominee Gary Johnson Gary Earl JohnsonWhat the numbers say about Trump's chances at reelection Presidential race tightens in Minnesota as Trump plows resources into state The Hill's Campaign Report: Biden condemns violence, blames Trump for fomenting it l Bitter Mass. primaries reach the end l Super PAC spending set to explode MORE is backed by 10 percent and Green Party nominee Jill Stein is supported by 3 percent of likely voters.

In a head-to-head matchup, Clinton has a 7-point lead over her Republican rival, 51 to 44 percent.

Clinton has an advantage among voters under age 40 in a four-way matchup, 49 to 26 percent. Johnson is backed by 16 percent of voters ages 18 to 29 and Stein is supported by 7 percent.

Among voters ages 65 and over, Trump has a slight lead over Clinton, 47 to 43 percent. Only 6 percent of voters ages 65 and older are supporting Johnson or Stein, according to the poll.

The poll was conducted from Sept. 19 to 25 among 13,598 adults who are likely to vote. The margin of error is 1.1 percent.

According to the RealClearPolitics average of polls, Clinton has a 1.7-point lead over Trump in a four-way matchup, 42.9 to 41.2 percent.

Several recent polls have shown the candidates in a tight race for the White House ahead of the first presidential debate Monday night.