Midterm Election Polls: Final Look At Senate Races In Texas, Florida, Tennessee And Others

While there has been talk of a "blue wave" in 2018, Democrats on Election Day remain underdogs to gain a majority in the Senate.

However, final polls for races in Arizona, Florida, Indiana, Missouri and Nevada and others remain within the margin of error of 4 points or less, which means they are too close to predict. To gain the majority of the Senate, Democrats must defend their current seats while winning two Republican-held seats.

According to an NBC News/Marist poll, in Missouri, Democratic Sen. Claire McCaskill currently leads state attorney general and Republican challenger Josh Hawley. McCaskill shows 50 percent support to Hawley’s 47 percent. After President Trump won Missouri by nearly 20 percentage points in 2016, there have been worries for Democrats that McCaskill could lose her seat.

In Indiana’s tight race, Republican challenger and pro-Trump businessman Mike Braun, has pegged Democratic incumbent Sen. Joe Donnelly as a "career politician who will say anything to keep his job." Donnelly is hoping to keep his seat in a state where Trump won by 19 points in 2016 by touting he voted for Trump 62 percent of the time. A recent Fox News poll had Donnelly leading by 7 points, while an NBC News/Marist poll had Donnelly leading by 2 points.

Democrats have a slim lead in Florida, where Democrat incumbent Sen. Bill Nelson faces a tough challenge from current Republican Gov. Rick Scott. The Trafalgar Group listed Scott with a lead of 2 points, while Emerson College had Nelson up by 4 points. According to RealClearPolitics.com, Nelson has an average lead of 2.4 points. Trump won Florida in 2016 by just 1.2 points.

Many eyes will be on Arizona and Nevada where Democrats hope to win tight races.

In Arizona, Republican Rep. Martha McSally and Democrat Rep. Kyrsten Sinema are in a heated battle for the open seat left by retiring Republican Sen. Jeff Flake. Sinema positioned herself as a centrist while McSally leaned on her military service. The race has been too tight to predict for weeks for the first woman senator in Arizona's 106-year history. In 2016, Trump won the state by 3.5 percentage points. The Trafalgar Group has McSally leading by 2 points, while Emerson College has Sinema leading by 1 point.

In Nevada, a state where senators have a track record of winning re-elections, Republican Sen. Dean Heller is seeking a second term against Democratic Rep. Jacky Rosen. In 2016, Hillary Clinton won Nevada by over 27,000 votes. Emerson College has Rosen leading by 4 points, while the Trafalgar Group has Heller leading by 3 points.

Texas might have the most contentious race of the midterms. Democratic Rep. Robert "Beto" O’Rourke is looking to unseat Republican Sen. Ted Cruz. While Cruz has led in every poll, O'Rourke has generated large crowds at rallies throughout the state. The last Quinnipiac University poll had Cruz up by 5 points. The Trafalgar Group has Cruz leading by 8.7 points, while Emerson College has the former presidential candidate with just a lead of 3 points.

Another prominent race is in Tennessee, where former Gov. Phil Bredesen, a centrist Democrat and friend of retiring Republican Sen. Bob Corker, is challenging Republican Rep. Marsha Blackburn, who was endorsed by President Trump. An Emerson College poll has Blackburn with an advantage of 8 points, while Fox News has Blackburn up by 9 points. But an East Tennessee State University poll had the race even. In 2016, Trump won both Texas and Tennessee by sizable margins.

Polling hours vary within each state, with the first poll closings in Indiana and Kentucky at 6 p.m. ET.