Incumbent Sen. Claire McCaskill Claire Conner McCaskillMomentum growing among Republicans for Supreme Court vote before Election Day Democratic-linked group runs ads in Kansas GOP Senate primary Trump mocked for low attendance at rally MORE (D) holds a slim 3-point lead over Republican challenger and Missouri Attorney General Josh Hawley ahead of Tuesday's midterm elections, according to a new poll.

McCaskill has the support of 50 percent of likely voters polled, while 47 percent back Hawley, according to the NBC News/Marist poll published Monday. McCaskill's lead is within the poll's margin of error of 5.2 percentage points.

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In the previous NBC News/Marist poll published in September, the two candidates were tied, with each getting the support of 47 percent of likely voters.

According to the Monday poll, McCaskill has a 20-point edge among independents and a 13-point lead among women in a head-to-head matchup with Hawley.

Lee Miringoff, director of the Marist College Institute for Public Opinion, told NBC News that Missouri "is politically split down the middle."

“Republicans are hoping to emerge with their red state status intact while Democrats are hoping to score an upset. Independents are in the driver’s seat, and right now they’re leaning towards the Democrats," he said.

Another poll published Monday, however, showed Hawley with a 4-point lead in the race. According to the Trafalgar Group poll, 48.3 percent of likely voters support Hawley and 44.4 percent are likely to vote for McCaskill.

McCaskill, who is one of 10 Senate Democrats up for reelection in states President Trump won in 2016, is one of the most vulnerable incumbents in Tuesday's elections.

Hawley has been endorsed by Trump and has closely aligned himself with the president during the campaign.