“Trump’s approval ratings have definitely been on the lower end of his historic range,” said Jennifer Duffy, senior editor of The Cook Political Report, a nonpartisan publication that tracks Senate races.

“If you’re Susan Collins or Martha McSally or Cory Gardner this does not help the cause of your reelection to have to take these votes. It doesn’t help,” she said.

John Weaver, a longtime strategist to the late Sen. John McCain (R-Ariz.) said he “definitely” thinks the impeachment debate will have an impact on Senate races.

“I think impeachment is playing and will play an important role in the shaping of the future of the Senate,” Weaver said. “The president is underwater with his job approval in certain states and many of those states happen to be ones where Republican members are polling in the 30s and low 40s with their reelect — and those states include Arizona and Colorado and North Carolina and Maine, for example.”