Biden opens 9-point lead over Trump in Senate battlegrounds: poll

Former Vice President Joe Biden has opened up a 9-point lead over President Trump in six states where Republican senators face difficult reelection battles this fall, according to a new poll.

The survey from Hart Research Associates finds Biden at 50 percent and Trump at 41 percent among voters sampled in Arizona, Colorado, Iowa, Maine, Montana and North Carolina.

Trump won four of those states in 2016, with the exception of Maine and Colorado. All six states feature vulnerable GOP incumbents: Sens. Marth McSally (Ariz.), Cory Gardner (Colo.), Joni Ernst (Iowa), Susan Collins (Maine), Steve Daines (Mont.) and Thom Tillis (N.C.).