Florida Democratic gubernatorial candidate Andrew Gillum speaks during a debate in Tampa, Florida, October 21, 2018. Chris O'Meara | Pool | Reuters

Democrats hold slim leads in Florida's pivotal statewide races in the final push to Tuesday's midterm elections, a poll released Monday found. In a Senate race that will help to determine control of the chamber, incumbent Democrat Bill Nelson leads Republican Gov. Rick Scott by 4 percentage points, according to the NBC News/Marist survey. The Democrat garners 50 percent of support among likely voters, versus 46 percent for his GOP challenger. Four percent are undecided. Democratic Tallahassee Mayor Andrew Gillum leads the Florida gubernatorial contest by the same margin over Republican former Rep. Ron DeSantis, a staunch supporter of President Donald Trump. Their leads fall within the 5 percentage point margin of error for likely voters. The swing state survey bodes well for Democrats in a midterm in which they hope to challenge for control of both chambers of Congress and flip several governor's offices. A Nelson win would limit the GOP's potential to boost its 51-49 majority in the Senate — and Trump's ability to push his legislative priorities through Congress. In a state Trump won in 2016, only 44 percent of likely voters approve of the job the president is doing, while 51 percent disapprove, the poll found. A victory by Gillum, Florida's first black gubernatorial candidate, would change party control of the state governor's office. He could pursue policies such as the expansion of the federal and state Medicaid insurance program for low-income people.

Nelson and Gillum lead among independents, African-Americans, Latinos and women. Scott and DeSantis have an edge among whites, men and seniors. In a state where nonpartisan forecasters consider six House races competitive, likely voters also narrowly favor Democratic control of Congress. Forty-nine percent say they prefer a legislative branch controlled by Democrats, while 45 percent would rather see GOP majorities. When asked which party they are more likely to vote for in their own congressional districts, 51 percent of likely voters say the Democrat, while 46 prefer the Republican. Democrats aim to pick up a net 23 GOP-held seats in the House to win a majority. They have a chance to convert multiple seats in Florida, including the South Florida 27th and 26th Districts that Democrat Hillary Clinton won in the 2016 presidential contest.

In the statewide races, likely voters have better views of the Democratic candidates than their Republican opponents. Forty-five percent say they have a favorable impression of Nelson, while 42 percent have an unfavorable view of him. The 76-year-old Nelson is seeking his fourth term in the Senate. Forty-two percent of likely voters see Scott favorably, versus 50 percent who view him unfavorably. Scott, 65, has been governor for two terms. Locally, the governor has faced backlash both for his handling of an algae crisis in the state and potential conflicts of interest due to the structure of a so-called blind trust he set up for his business assets. Forty-eight percent of likely voters have a favorable impression of Gillum, while 40 percent see him unfavorably. He has been mayor of Tallahassee, the state capital, since 2014. Gillum faces accusations of corruption due to an FBI investigation into development in Tallahassee. The mayor has said the probe does not target him personally. Forty-three percent have a favorable view of DeSantis, versus 45 percent who have an unfavorable impression. DeSantis was in Congress from 2013 until earlier this year, when he resigned to run for governor.