Here are the country's most and least popular senators

REUTERS/Aaron P. Bernstein

Senate Majority Leader Mitch McConnell and Sen. John Cornyn (R-TX) arrive to speak with reporters following the party luncheons on Capitol Hill in Washington, U.S. November 14, 2017.

• Several vulnerable Democratic senators, including Bill Nelson of Florida, Claire McCaskill of Missouri, and Joe Donnelly of Indiana, saw net drops in their approval ratings in the third quarter of this year.
• Nelson and Sen. Bob Menendez, who's expected to win reelection in New Jersey after being acquitted of federal corruption charges this year, saw the biggest drops in approval.
• Sens. Bernie Sanders, the Vermont independent, and Mitch McConnell, the Republican majority leader from Kentucky, held on to their titles as the most and least popular senators, respectively.

As 26 Democratic and nine Republican senators seek reelection in November, the chamber's most vulnerable members made few gains in their approval ratings in the last quarter, according to a new Morning Consult poll.

Sen. Bill Nelson, the Florida Democrat running for reelection in a competitive race against Republican Gov. Rick Scott (R), saw the biggest drop in approval numbers of any senator: 12 points since last quarter's poll. It's also the first underwater rating for Nelson - 39% approve of him and 41% disapprove - since Morning Consult began conducting this quarterly poll in 2015.

Democratic Sens. Bob Menendez of New Jersey, Claire McCaskill of Missouri, and Joe Donnelly of Indiana - all up for reelection - also saw steep drops in their approval ratings, while Sen. Dean Heller, the Nevada Republican facing a strong challenge, saw a four-point drop.

Sens. Bernie Sanders, the Vermont independent, and Mitch McConnell, the Republican majority leader from Kentucky, held on to their titles as the most and least popular senators, respectively. The pair held these titles throughout 2017 and 2018, but McConnell saw his approval rating increase by eight points since last quarter's poll.

The poll surveyed 359,057 registered voters between July 1 and Sept. 25 nationwide.

Check out the top five most and least popular senators below.